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-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/README.md38
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.gifbin0 -> 8077401 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.py77
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.gifbin0 -> 2552938 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.py88
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.gifbin0 -> 2198637 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.py73
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Relative_Maximum_and_Relative_Minimum.gifbin0 -> 1587319 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Relative_Maximum_and_Relative_Minimum.py51
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_Saddle_Point.gifbin0 -> 7136893 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_Saddle_Point.py71
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file6_f(x,y)=(y-x)(1-2x-3y).gifbin0 -> 1522415 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file6_f(x,y)=(y-x)(1-2x-3y).py29
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/README.md20
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.gifbin0 -> 456997 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.py45
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-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.py89
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Constraints_g_and_h.gifbin0 -> 1740442 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Constraints_g_and_h.py41
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Critical_Points_mcq_questions.pdf (renamed from FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical_Points_mcq_questions.pdf)bin414750 -> 414750 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Lagrange_Multipliers_mcq_questions.pdfbin0 -> 422605 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Tangent_Plane_Approximations_mcq_questions.pdfbin0 -> 424626 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/The_Second_Derivative_Test_mcq_questions.pdf (renamed from FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The_Second_Derivative_Test_MCQ.pdf)bin646880 -> 646880 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Total_Differential_mcq_questions.pdfbin0 -> 426164 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/README.md26
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.gifbin0 -> 827096 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.py50
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.gifbin0 -> 979487 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py85
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file3_Non_Differentiable_Function.gifbin0 -> 708466 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file3_Non_Differentiable_Function.py47
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.gifbin0 -> 1424279 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.py62
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/README.md27
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.gifbin0 -> 3166332 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.py78
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Nondegenerate_Hessian_Matrix.gifbin0 -> 2047897 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Nondegenerate_Hessian_Matrix.py158
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Degenerate_Hessian_Matrix.gifbin0 -> 407350 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Degenerate_Hessian_Matrix.py45
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.gifbin0 -> 1140109 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.py120
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/README.md34
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.gifbin0 -> 565199 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.py59
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.gifbin0 -> 729982 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.py77
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.gifbin0 -> 1444924 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.py100
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file4_total_differential_change.gifbin0 -> 300675 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file4_total_differential_change.py54
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.gifbin0 -> 423246 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.py52
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diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/README.md b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/README.md
new file mode 100644
index 0000000..857d298
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/README.md
@@ -0,0 +1,38 @@
+<h1><div align=”center”><b>SubTopic: Critical Points</b></h1></div>
+<br/></br>
+
+<tab>file1_Critical_Point_of_a_function
+
+![file1_Critical_Point_of_a_function](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file2_Traces_and_Tangent
+
+![file2_Traces_and_Tangent](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file3_Tangent_plane_at_extrema_of_a_function
+
+![file3_Tangent_plane_at_extrema_of_a_function](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file4_Relative_Maximum_and_Relative_Minimum
+
+![file4_Relative_Maxima_and_Relative_Minima](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Relative_Maximum_and_Relative_Minimum.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file5_Saddle_Point
+
+![file5_Saddle_Point](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_Saddle_Point.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file6_f(x,y)=(y-x)(1-2x-3y)
+
+![file6_f(x,y)=(y-x)(1-2x-3y)](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file6_f(x%2Cy)%3D(y-x)(1-2x-3y).gif?raw=true)
+<br/></br>
+<br/></br>
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.gif
new file mode 100644
index 0000000..ca3989c
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.gif
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diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.py
new file mode 100644
index 0000000..e8cb08d
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.py
@@ -0,0 +1,77 @@
+from manimlib.imports import*
+import math as m
+
+#---- case 1: parial derivatives exist at critical point of the function
+class firstScene(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.5,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5) #---- y axis
+
+ #---- f(x,y) = e^(-10x^2-10y^2)
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ m.exp(-10*u**2-10*v**2)
+ ]),u_min = -1, u_max = 1, v_min = -1, v_max = 1, checkerboard_colors = [TEAL_E,TEAL_D,TEAL_C,TEAL_B]).fade(0.6).scale(3.5).shift([0,0,1.5])
+
+ l1 = Line([0,0,3.75],[0,0,0],color = '#800000')
+
+ d = Dot([0,0,3.75],color = '#800000') #---- critical point
+
+ d_text = TextMobject("$\\frac{\\partial f}{\\partial x}=\\frac{\\partial f}{\\partial y} = 0$").scale(0.8).to_corner(UL)
+
+ f_text = TextMobject("Critical Point ",color = YELLOW).shift(3.4*UP).scale(0.5)
+
+ self.set_camera_orientation(phi = 45*DEGREES, theta = 40*DEGREES)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.add_fixed_in_frame_mobjects(d_text)
+ self.begin_ambient_camera_rotation(rate = 0.2)
+ self.play(Write(surface))
+ self.wait(1)
+ self.play(Write(l1))
+ self.play(Write(d))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(f_text)
+ self.wait(3)
+ self.play(FadeOut(f_text),FadeOut(surface),FadeOut(axes),FadeOut(d_text),FadeOut(d),FadeOut(l1),FadeOut(label_x),FadeOut(label_y))
+
+
+#---- case 2: parial derivatives do not exist at critical point of the function
+class secondScene(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.5,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5) #---- y axis
+
+ #---- g(x,y)= |x|+|y|
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ abs(u)+abs(v)
+ ]),u_min = -1.5, u_max = 1.5, v_min = -1.5, v_max = 1.5, checkerboard_colors = [TEAL_E,TEAL_D,TEAL_C,TEAL_B])
+
+ d2 = Dot([0,0,0],color = '#800000') #---- critical point
+
+ d2_text = TextMobject("$\\frac{\\partial f}{\\partial x}$ and/or $\\frac{\\partial f}{\\partial y}$ does not exist").scale(0.7).to_corner(UL)
+
+ g_text = TextMobject("Critical Point",color = YELLOW).shift(1.2*RIGHT).scale(0.6)
+
+ self.set_camera_orientation(phi = 60*DEGREES, theta = 40*DEGREES)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.add_fixed_in_frame_mobjects(d2_text)
+ self.begin_ambient_camera_rotation(rate = 0.2)
+ self.wait(1)
+ self.play(Write(surface2))
+ self.wait(1)
+ self.play(Write(d2))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(g_text)
+ self.wait(2)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.gif
new file mode 100644
index 0000000..84acf2e
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.gif
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diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.py
new file mode 100644
index 0000000..4b020e1
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.py
@@ -0,0 +1,88 @@
+from manimlib.imports import*
+import math as m
+
+#---- tangent to the trace with x constant
+class firstScene(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes().scale(1)
+ label_x = TextMobject("$x$").shift([5.8,-0.5,0])
+ label_y = TextMobject("$y$").shift([-0.5,-5.6,0]).rotate(-4.5)
+
+ #---- graph of f(x,y) = -x^2-y^2
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -u**2-v**2
+ ]),u_min=-1,u_max=1, v_min=-1,v_max=1,checkerboard_colors=[PURPLE_C,PURPLE_D,PURPLE_E,PURPLE_B]).scale(1.5).shift([0,0,2]).rotate(0.2)
+
+ #---- curve(trace) along y axis
+ curve = ParametricSurface(
+ lambda u, v: np.array([
+ u*0.4,
+ v,
+ -v**2
+ ]),v_min =-1 , v_max =1 , u_min = -0.1, u_max = 0.1).scale(1.6).shift([0.02,0.1,2.3]).set_color("#800000").rotate(0.1)
+
+ d = Dot(color =YELLOW).shift([-0.05,-0.2,2.3]) #---- critical point
+
+ x_text = TextMobject("Tangent to the trace with $x$ constant at critical point").shift(3*RIGHT+2*UP).scale(0.5).to_corner(UL)
+
+ tangent_line = Line([-0.05,-1.5,2.3],[-0.05,1.5,2.3],color = '#228B22')
+
+ self.add(axes)
+ self.set_camera_orientation(phi = 40 * DEGREES, theta = 55 * DEGREES)
+ self.begin_ambient_camera_rotation(rate = 0.1)
+ self.add(label_x)
+ self.add(label_y)
+ self.play(Write(surface))
+ self.add_fixed_in_frame_mobjects(x_text)
+ self.add(curve)
+ self.wait(1)
+ self.play(Write(tangent_line),Write(d))
+ self.wait(1)
+
+
+
+#---- tangent to the trace with y constant
+class secondScene(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes().scale(1)
+ label_x = TextMobject("$x$").shift([5.8,-0.5,0])
+ label_y = TextMobject("$y$").shift([-0.5,-5.6,0]).rotate(-4.5)
+
+ #---- graph of f(x,y) = -x^2-y^2
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -u**2-v**2
+ ]),u_min = -1, u_max = 1, v_min = -1, v_max = 1, checkerboard_colors = [PURPLE_B,PURPLE_C,PURPLE_D,PURPLE_E]).scale(1.5).shift([0,0,2]).rotate(0.2)
+
+ #---- curve(trace) along x axis
+ curve = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v*0.4,
+ -u**2
+ ]),v_min = -0.1, v_max = 0.1, u_min = -1, u_max = 1).scale(1.6).shift([0.07,0.1,2.3]).set_color("#800000")
+
+ d = Dot(color = YELLOW).shift([0,-0.2,2.3]) #---- critical point
+
+ tangent_line = Line(color = '#228B22').scale(1).shift([0,-0.2,2.3]).rotate(m.radians(190),LEFT)
+
+ y_text = TextMobject("Tangent to the trace with $y$ constant at critical point").shift(3*RIGHT+2*UP).scale(0.5).to_corner(UL)
+
+ self.add(axes)
+ self.set_camera_orientation(phi = 40 * DEGREES, theta = 55 * DEGREES)
+ self.add(label_x)
+ self.add(label_y)
+ self.begin_ambient_camera_rotation(rate = 0.1)
+ self.play(Write(surface))
+ self.add_fixed_in_frame_mobjects(y_text)
+ self.add(curve)
+ self.wait(1.5)
+ self.play(Write(tangent_line),Write(d))
+ self.wait(0.5)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.gif
new file mode 100644
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diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.py
new file mode 100644
index 0000000..e674113
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.py
@@ -0,0 +1,73 @@
+from manimlib.imports import*
+
+#---- tangent plane to minima of the function
+class firstScene(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.5,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5) #---- y axis
+
+ #---- parabola: f(x,y) = x**2 + y**2
+ parabola = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u**2+v**2
+ ]),v_min = -1, v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [GREEN_E,GREEN_D,GREEN_C,GREEN_B], resolution = (20, 20)).scale(1)
+
+ d = Dot(np.array([0,0,0]), color = '#800000') # ---- critical point
+
+ tangent_plane = Rectangle(fill_color = '#C0C0C0', fill_opacity = 0.3).move_to(ORIGIN).fade(0.7) # ----tangent plane
+
+ parabola_text = TextMobject("Minimum with horizontal tangent plane").scale(0.7).to_corner(UL)
+
+ self.set_camera_orientation(phi = 75 * DEGREES, theta = 45 * DEGREES)
+ self.begin_ambient_camera_rotation(rate = 0.2)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.add_fixed_in_frame_mobjects(parabola_text)
+ self.wait(1)
+ self.play(Write(parabola))
+ self.play(ShowCreation(d))
+ self.wait(1)
+ self.play(ShowCreation(tangent_plane))
+ self.wait(2)
+ self.play(FadeOut(parabola_text),FadeOut(parabola),FadeOut(tangent_plane),FadeOut(d),FadeOut(label_x),FadeOut(label_y),FadeOut(axes))
+
+
+#---- tangent plane to maxima of the function
+class secondScene(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.5,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5) #---- y axis
+
+ #----parabola: g(x,y) = -x**2-y**2
+ parabola = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -u**2-v**2
+ ]),v_min = -1, v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [BLUE_E,BLUE_D,BLUE_C,BLUE_B], resolution = (20, 20)).scale(1)
+
+ d = Dot(np.array([0,0,0]), color = '#800000') #---- critical point
+
+ tangent_plane = Rectangle(fill_color = '#C0C0C0',fill_opacity = 0.3).move_to(ORIGIN).fade(0.7) #---- tangent plane
+
+ parabola_text = TextMobject("Maximum with horizontal tangent plane").scale(0.7).to_corner(UL)
+
+ self.set_camera_orientation(phi = 75 * DEGREES, theta = 45 * DEGREES)
+ self.begin_ambient_camera_rotation(rate = 0.2)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.add_fixed_in_frame_mobjects(parabola_text)
+ self.wait(1)
+ self.play(Write(parabola))
+ self.play(ShowCreation(d))
+ self.wait(1)
+ self.play(ShowCreation(tangent_plane))
+ self.wait(2)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Relative_Maximum_and_Relative_Minimum.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Relative_Maximum_and_Relative_Minimum.gif
new file mode 100644
index 0000000..6b93359
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Relative_Maximum_and_Relative_Minimum.gif
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diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Relative_Maximum_and_Relative_Minimum.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Relative_Maximum_and_Relative_Minimum.py
new file mode 100644
index 0000000..3bd810d
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Relative_Maximum_and_Relative_Minimum.py
@@ -0,0 +1,51 @@
+from manimlib.imports import*
+import math as m
+
+#---- locating extrema of a funtion using critical points
+class Extrema(ThreeDScene):
+ def construct(self):
+
+ h_text = TextMobject("Relative Maximum and Relative Minimum",color = GREEN)
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.3,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.3,5.5,0]).rotate(-4.5) #---- y axis
+
+ #---- f(x,y) = 5(x+y)e^(-x^2-y^2)
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ 5*(u+v)*m.exp(-u**2-v**2)
+ ]),u_min = -PI, u_max = PI, v_min = -PI, v_max = PI).set_color(TEAL).shift([0,0,0]).fade(0.4)
+
+ d1 = Dot(color = YELLOW).shift([0.5,0.5,3.02]) #---- critical point for maxima
+ l1 = Line([0.5,0.5,0.1],[0.5,0.5,3],color = YELLOW)
+
+ d2 = Dot(color = YELLOW).shift([-1.15,0,-2.98]) #---- critical point for minima
+ l2 = Line([-1.15,0,0],[-1.15,0,-2.98],color = YELLOW)
+
+ max_text = TextMobject("Relative Maximum").shift(3.1*UP+1.5*RIGHT).scale(0.5)
+ min_text = TextMobject("Relative Minimum").shift(3.1*DOWN+1.5*LEFT).scale(0.5)
+
+ self.add_fixed_in_frame_mobjects(h_text)
+ self.wait(1)
+ self.wait(1)
+ self.play(FadeOut(h_text))
+ self.wait(1)
+ self.set_camera_orientation(phi = 100*DEGREES, theta = -40*DEGREES)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.play(Write(surface))
+ self.wait(1)
+ self.play(Write(l1),Write(d1))
+ self.add_fixed_in_frame_mobjects(max_text)
+ self.wait(1)
+ self.play(Write(l2),Write(d2))
+ self.add_fixed_in_frame_mobjects(min_text)
+ self.wait(1)
+ self.wait(1)
+ self.play(FadeOut(l1),FadeOut(d1),FadeOut(l2),FadeOut(d2),FadeOut(max_text),FadeOut(min_text))
+ self.begin_ambient_camera_rotation(rate = 0.3)
+ self.wait(3)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_Saddle_Point.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_Saddle_Point.gif
new file mode 100644
index 0000000..7300f3a
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_Saddle_Point.gif
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diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_Saddle_Point.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_Saddle_Point.py
new file mode 100644
index 0000000..67dbb18
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_Saddle_Point.py
@@ -0,0 +1,71 @@
+from manimlib.imports import*
+import math as m
+
+#---- saddle point of a function
+class SaddlePoint(ThreeDScene):
+ def construct(self):
+
+ h_text = TextMobject("Saddle Point",color = GREEN)
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.3,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.3,5.5,0]).rotate(-4.5) #---- y axis
+
+ #---- f(x,y) = -x^2-y^2
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u**2-v**2
+ ]),u_min = -1, u_max = 1, v_min = -1, v_max = 1,checkerboard_colors = [BLUE_B,BLUE_C,BLUE_D,BLUE_E]).shift([0,0,0]).scale(3)
+
+ #---- curve(trace) along y axis
+ curve_x = ParametricSurface(
+ lambda u, v: np.array([
+ u*0.1,
+ v,
+ v**2
+ ]),v_min = -1, v_max = 1, u_min = -0.2, u_max = 0.2).shift([0,0,-2]).scale(3.1).set_color("#800000").rotate(m.radians(180),UP)
+
+ x_text = TextMobject("A dip at critical point along x axis").scale(0.5).to_corner(UL)
+
+ #---- curve(trace) along x axis
+ curve_y = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v*0.1,
+ -u**2
+ ]),v_min = -0.2, v_max = 0.2, u_min = -1, u_max = 1).scale(3).shift([0.1,0,2.2]).set_color("#800000").rotate(m.radians(182),DOWN)
+
+ y_text = TextMobject("A peak at critical point along y axis").scale(0.5).to_corner(UL)
+
+ d = Dot(color = YELLOW).shift([0,-0.22,0]) #---- critical point(saddle point)
+
+ self.add_fixed_in_frame_mobjects(h_text)
+ self.wait(1)
+ self.play(FadeOut(h_text))
+ self.wait(1)
+ self.set_camera_orientation(phi = 75*DEGREES, theta = 40*DEGREES)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.play(Write(surface))
+ self.wait(1)
+ self.move_camera(phi = 45*DEGREES, theta = 70*DEGREES)
+ self.add(curve_y)
+ self.play(Write(d))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(x_text)
+ self.wait(1)
+ self.wait(1)
+ self.play(FadeOut(curve_y),FadeOut(d),FadeOut(x_text))
+ self.wait(1)
+ self.move_camera(phi = 40*DEGREES, theta = 30*DEGREES)
+ self.add(curve_x)
+ self.play(Write(d))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(y_text)
+ self.begin_ambient_camera_rotation(rate = 0.3)
+ self.wait(3)
+ self.play(FadeOut(curve_x),FadeOut(d),FadeOut(y_text))
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file6_f(x,y)=(y-x)(1-2x-3y).gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file6_f(x,y)=(y-x)(1-2x-3y).gif
new file mode 100644
index 0000000..4bc92f8
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file6_f(x,y)=(y-x)(1-2x-3y).gif
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diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file6_f(x,y)=(y-x)(1-2x-3y).py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file6_f(x,y)=(y-x)(1-2x-3y).py
new file mode 100644
index 0000000..41c3b61
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file6_f(x,y)=(y-x)(1-2x-3y).py
@@ -0,0 +1,29 @@
+from manimlib.imports import*
+
+#---- visualization of the function
+class ExampleAnimation(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.5,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5) #---- y axis
+
+ #---- f(x,y) = (y-x)(1-2x-3y)
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ (v-u)*(1-2*u-3*v)
+ ]),v_min = -1, v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [PURPLE_B,PURPLE_C,PURPLE_D, PURPLE_E]).scale(1).fade(0.2).shift([0.2,0.2,0])
+
+ f_text = TextMobject("$f(x,y) = (y-x)(1-2x-3y)$").to_corner(UL)
+
+ self.set_camera_orientation(phi = 60 * DEGREES, theta = 75 * DEGREES)
+ self.begin_ambient_camera_rotation(rate=0.1)
+ self.add_fixed_in_frame_mobjects(f_text)
+ self.wait(1)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.wait(1)
+ self.play(Write(f))
+ self.wait(4)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/README.md b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/README.md
new file mode 100644
index 0000000..05ff51d
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/README.md
@@ -0,0 +1,20 @@
+<h1><div align=”center”><b>SubTopic: Lagrange Multipliers</b></h1></div>
+<br/></br>
+
+<tab>file1_Extrema_over_g(x,y)=k
+
+![file1_Extrema_over_g(x,y)=k](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x%2Cy)%3Dk.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file2_Geometric_Proof
+
+![file2_Geometric_Proof](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file3_Constraints_g_and_h
+
+![file3_Constraints_g_and_h](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Constraints_g_and_h.gif?raw=true)
+<br/></br>
+<br/></br>
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.gif
new file mode 100644
index 0000000..d423943
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.py
new file mode 100644
index 0000000..a01efb0
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.py
@@ -0,0 +1,45 @@
+from manimlib.imports import*
+import math as m
+
+#---- optimizing funtion f(x,y) w.r.t to g(x,y)
+class ConstrainedExtrema(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes().fade(0.4)
+ label_x = TextMobject("$x$").shift([5.5,-0.5,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5) #---- y axis
+
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u**2+v**2+u**3-v**3
+ ]),u_min=-0.5,u_max=0.5, v_min=-0.5,v_max=0.5).scale(5).shift([0,1,2.5]).set_color(TEAL).fade(0.2)
+
+ c = Circle(color='#FF00FF',fill_opacity=0.3).shift([-0.4,0,1.5]).rotate(1.9,UP).scale(0.7)
+
+ minima = Dot(color = '#4169E1').shift([-0.5,0.5,1]).rotate(1.571,UP)
+ maxima = Dot(color = '#4169E1').shift([0.1,0,2.2]).rotate(1.571,UP)
+
+ max_text = TextMobject("maximum over $g(x,y)=k$",color = '#FFA074').scale(0.6).shift(2.3*UP+2*LEFT)
+ min_text = TextMobject("minimum over $g(x,y)=k$",color = '#FFA074').shift([2.5,0.5,1]).scale(0.6).shift(0.5*UP)
+ label_f = TextMobject("$z=f(x,y)$",color=TEAL).scale(0.8).shift(3*UP+3*RIGHT)
+ label_g = TextMobject("g(x,y)=k",color = PURPLE).scale(0.5).shift(1.5*UP+0.8*LEFT)
+
+
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.set_camera_orientation(phi=75*DEGREES,theta=45*DEGREES)
+ self.play(Write(surface))
+ self.add_fixed_in_frame_mobjects(label_f)
+ self.wait(2)
+ self.play(Write(c))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(label_g)
+ self.wait(1)
+ self.play(Write(maxima))
+ self.add_fixed_in_frame_mobjects(max_text)
+ self.wait(1)
+ self.play(Write(minima))
+ self.add_fixed_in_frame_mobjects(min_text)
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.gif
new file mode 100644
index 0000000..e028a81
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.py
new file mode 100644
index 0000000..2c1d668
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.py
@@ -0,0 +1,89 @@
+from manimlib.imports import*
+
+#---- visualization of geometric proof of Lagrange multiplier
+class firstScene(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes().scale(0.7).rotate(math.radians(180))
+ label_x = TextMobject("$x$").shift(4*RIGHT).fade(0.4) #---- x axis
+ label_y = TextMobject("$y$").shift(3.2*DOWN+0.2*RIGHT).rotate(math.radians(180)).fade(0.4) #---- y axis
+
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ 1*np.sin(u)*np.cos(v),
+ 1*np.sin(u)*np.sin(v),
+ -1*np.sin(u)*np.sin(u)+2
+ ]),u_min=0,u_max=PI/2,v_min=0,v_max=2*PI).set_color(GREEN).scale(1).shift([-1.5,-1.5,0])
+
+ d = Dot([-2,-2.55,0],color = '#800000')
+ a_df = Arrow(color = '#00FFFF').rotate(-2).shift(3.2*DOWN+2.3*LEFT) #---- f parallel to g
+ a_dg = Arrow(color = '#FF00FF').scale(0.8).shift(3.2*DOWN+2.3*LEFT).rotate(-2) #---- f parallel to g
+
+ b_dg = Arrow(color = '#00FFFF').rotate(1.1).shift(0.82*LEFT+0.15*UP) #---- f parallel to g
+ b_df = Arrow(color = '#FF00FF').scale(0.6).rotate(-2).shift(1.43*LEFT+1.1*DOWN) #---- f parallel to g
+
+
+ qd = Dot(color = '#800000').shift(1.2*LEFT+0.6*DOWN)
+
+ l1 = Line([-1,-3.1,0],[-4,-3.1,0],color = PINK).rotate(-0.3).fade(0.6)
+ l2 = Line([-0.9,-2.9,0],[-4,-2.9,0],color = PINK).rotate(-0.3).fade(0.6)
+ l3= Line([-0.8,-2.7,0],[-4,-2.7,0],color = PINK).rotate(-0.3).fade(0.6)
+ l4= Line([-0.7,-2.45,0],[-4,-2.45,0],color = PINK).rotate(-0.3).fade(0.6)
+ l5= Line([-0.6,-2.2,0],[-4,-2.25,0],color = PINK).rotate(-0.3).fade(0.6)
+ l6 = Line([-0.5,-2,0],[-4,-2,0],color = PINK).rotate(-0.3).fade(0.6)
+ l7 = Line([-0.4,-1.8,0],[-4,-1.8,0],color = PINK).rotate(-0.3).fade(0.6)
+ l8 = Line([-0.3,-1.6,0],[-4,-1.6,0],color = PINK).rotate(-0.3).fade(0.6)
+ l9= Line([-0.2,-1.4,0],[-4,-1.4,0],color = PINK).rotate(-0.3).fade(0.6)
+ l10= Line([-0.1,-1.2,0],[-4,-1.2,0],color = PINK).rotate(-0.3).fade(0.6)
+ l11 = Line([-0,-1,0],[-4,-1,0],color = PINK).rotate(-0.3).fade(0.6)
+ l12 = Line([-0,-0.8,0],[-4,-0.8,0],color = PINK).rotate(-0.3).fade(0.6)
+ l13= Line([-0,-0.55,0],[-4,-0.55,0],color = PINK).rotate(-0.3).fade(0.6)
+ l14= Line([-0,-0.35,0],[-4,-0.35,0],color = PINK).rotate(-0.3).fade(0.6)
+ l15= Line([-0.,-0.15,0],[-4,-0.15,0],color = PINK).rotate(-0.3).fade(0.6)
+
+ rel_text = TextMobject("$\\nabla f = \\lambda \\nabla g$",color = TEAL).shift([3,3.2,0]).scale(0.5)
+
+ f_text = TextMobject("$\\nabla f$",color = '#800000').shift([1,1,0]).scale(0.5)
+ g_text = TextMobject("$\\nabla g$").shift([1.2,-0.8,0]).scale(0.5)
+
+ p_text= TextMobject("$P$").shift([1.8,2.6,0]).scale(0.5)
+
+ l1_text = TextMobject("$w=$ 17").rotate(math.radians(180)).scale(0.4).shift(2.7*DOWN+4.36*LEFT)
+ l2_text = TextMobject("$w=$ 16").rotate(math.radians(180)).scale(0.4).shift(2.46*DOWN+4.36*LEFT)
+ l3_text = TextMobject("$w=$ 15").rotate(math.radians(180)).scale(0.4).shift(2.2*DOWN+4.36*LEFT)
+ l4_text = TextMobject("$w=$ 14").rotate(math.radians(180)).scale(0.4).shift(1.97*DOWN+4.36*LEFT)
+ l5_text = TextMobject("$w=$ 13").rotate(math.radians(180)).scale(0.4).shift(1.74*DOWN+4.36*LEFT)
+ l6_text = TextMobject("$w=$ 12").rotate(math.radians(180)).scale(0.4).shift(1.5*DOWN+4.36*LEFT)
+ l7_text = TextMobject("$w=$ 11").rotate(math.radians(180)).scale(0.4).shift(1.26*DOWN+4.36*LEFT)
+ l8_text = TextMobject("$w=$ 10").rotate(math.radians(180)).scale(0.4).shift(1.05*DOWN+4.36*LEFT)
+ l9_text = TextMobject("$w=$ 9").rotate(math.radians(180)).scale(0.4).shift(0.8*DOWN+4.32*LEFT)
+ l10_text = TextMobject("$w=$ 8").rotate(math.radians(180)).scale(0.4).shift(0.6*DOWN+4.32*LEFT)
+ l11_text = TextMobject("$w=$ 7").rotate(math.radians(180)).scale(0.4).shift(0.4*DOWN+4.32*LEFT)
+ l12_text = TextMobject("$w=$ 6").rotate(math.radians(180)).scale(0.4).shift(0.2*DOWN+4.32*LEFT)
+ l13_text = TextMobject("$w=$ 5").rotate(math.radians(180)).scale(0.4).shift(-0.02*DOWN+4.32*LEFT)
+ l14_text = TextMobject("$w=$ 4").rotate(math.radians(180)).scale(0.4).shift(-0.23*DOWN+4.32*LEFT)
+ l15_text = TextMobject("$w=$ 3").rotate(math.radians(180)).scale(0.4).shift(-0.44*DOWN+4.32*LEFT)
+
+ level_Curve = VGroup(l1,l1_text,l2,l2_text,l3,l3_text,l4,l4_text,l5,l5_text,l6,l6_text,l7,l7_text,l8,l8_text,l9,l9_text,l10,l10_text,l11,l11_text,l12,l12_text,l13,l13_text,l14,l14_text,l15,l15_text)
+
+ self.set_camera_orientation(phi=0 * DEGREES, theta = 90*DEGREES)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.wait(1)
+ self.add(surface)
+ self.wait(1)
+ self.play(ShowCreation(level_Curve))
+ self.wait(1)
+ self.play(ShowCreation(a_df),ShowCreation(a_dg),Write(d))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(rel_text)
+ self.add_fixed_in_frame_mobjects(p_text)
+ self.wait(1)
+ self.play(Write(qd))
+ self.wait(1)
+ self.play(ShowCreation(b_df))
+ self.add_fixed_in_frame_mobjects(f_text)
+ self.wait(1)
+ self.play(ShowCreation(b_dg))
+ self.add_fixed_in_frame_mobjects(g_text)
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Constraints_g_and_h.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Constraints_g_and_h.gif
new file mode 100644
index 0000000..0da30ad
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Constraints_g_and_h.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Constraints_g_and_h.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Constraints_g_and_h.py
new file mode 100644
index 0000000..742d6b5
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Constraints_g_and_h.py
@@ -0,0 +1,41 @@
+from manimlib.imports import*
+import math as m
+
+class firstScene(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.5,0]).fade(0.4) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5).fade(0.4) #---- y axis
+
+ #---- constraint g(x,y)
+ cylinder = ParametricSurface(
+ lambda u, v: np.array([
+ np.cos(TAU * u),
+ np.sin(TAU * u),
+ 2 * (v)
+ ]),checkerboard_colors=[YELLOW_C,YELLOW_D,YELLOW_E]).rotate(m.radians(-40),RIGHT).shift([0.5,0.5,0]).scale(0.8)
+
+ #---- constraint h(x,y)
+ plane = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u+v
+ ]),checkerboard_colors=[TEAL_C,TEAL_D,TEAL_E]).shift([0,0,0]).rotate(m.radians(-40),RIGHT).scale(2).fade(0.3)
+
+ figure = VGroup(cylinder,plane).rotate(m.radians(-45),DOWN).scale(1.5)
+
+ self.set_camera_orientation(phi=65*DEGREES,theta=45*DEGREES)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.wait(1)
+ self.play(Write(cylinder))
+ self.play(Write(plane))
+ self.wait(1)
+ self.begin_ambient_camera_rotation(rate=0.4)
+ self.wait(1)
+ self.wait(1)
+ self.play(FadeOut(label_x),FadeOut(label_y))
+ self.wait(1)
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical_Points_mcq_questions.pdf b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Critical_Points_mcq_questions.pdf
index 25c4e4d..25c4e4d 100644
--- a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical_Points_mcq_questions.pdf
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Critical_Points_mcq_questions.pdf
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Lagrange_Multipliers_mcq_questions.pdf b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Lagrange_Multipliers_mcq_questions.pdf
new file mode 100644
index 0000000..3ba7d1c
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Lagrange_Multipliers_mcq_questions.pdf
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Tangent_Plane_Approximations_mcq_questions.pdf b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Tangent_Plane_Approximations_mcq_questions.pdf
new file mode 100644
index 0000000..2a77b15
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Tangent_Plane_Approximations_mcq_questions.pdf
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The_Second_Derivative_Test_MCQ.pdf b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/The_Second_Derivative_Test_mcq_questions.pdf
index ca60cbf..ca60cbf 100644
--- a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The_Second_Derivative_Test_MCQ.pdf
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/The_Second_Derivative_Test_mcq_questions.pdf
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Total_Differential_mcq_questions.pdf b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Total_Differential_mcq_questions.pdf
new file mode 100644
index 0000000..b1a679d
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/MCQ-Questions/Total_Differential_mcq_questions.pdf
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/README.md b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/README.md
new file mode 100644
index 0000000..2a274d0
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/README.md
@@ -0,0 +1,26 @@
+<h1><div align=”center”><b>SubTopic: Tangent Plane Approximations</b></h1></div>
+<br/></br>
+
+<tab>file1_Tangent_Plane
+
+![file1_Tangent_Plane](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file2_Tangent_plane_approximation_visualization
+
+![file2_Tangent_plane_approximation_visualization](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file3_Non_Differentiable_Function
+
+![file3_Non_Differentiable_Function](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file3_Non_Differentiable_Function.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file4_Tangent_plane_at_extrema_and_saddle_point
+
+![file4_Tangent_plane_at_extrema_and_saddle_point](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.gif?raw=true)
+<br/></br>
+<br/></br>
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.gif
new file mode 100644
index 0000000..2b8bf5f
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.py
new file mode 100644
index 0000000..8efdbd2
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.py
@@ -0,0 +1,50 @@
+from manimlib.imports import*
+
+#---- tangent plane is parallel to the surface of the funtion at a point
+class tangentplane(ThreeDScene):
+ def construct(self):
+
+ s1_text=TextMobject("Suppose, the point $(x,y)$ lies on the surface of the function.").scale(0.5).shift(2*UP)
+ s2_text=TextMobject("When zooming on that point, the surface would appear more and more like a plane.").scale(0.5).shift(1*UP)
+ s3_text=TextMobject("This plane is called the tangent plane.").scale(0.5)
+
+ #---- graph of function f(x,y) = -x^2-y^2
+
+ f = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -u**2-v**2
+ ]),v_min = -1, v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [YELLOW_B,YELLOW_C,YELLOW_D, YELLOW_E]).shift([0,0,0]).scale(1)
+
+
+ d = Dot([0,0,0],color = '#800000') #---- critical point
+
+ r = Rectangle(color = PURPLE,fill_opacity=0.2).shift([0.1,0,0]).scale(0.3) #---- tangent plane
+
+ s = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -u**2-v**2
+ ]),v_min = -1, v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [YELLOW_B,YELLOW_C,YELLOW_D, YELLOW_E]).shift([0,0,0]).scale(3.5)
+
+ d2 = Dot([0,0,2.5],color = '#800000') #---- changing position of critical point
+
+ r2 = Rectangle(color = PURPLE,fill_opacity=0.5).shift([0.1,0,2.5]).scale(0.3) #---- changing position of tangent plane
+
+ self.set_camera_orientation(phi = 50 * DEGREES, theta = 45 * DEGREES)
+ self.add_fixed_in_frame_mobjects(s1_text)
+ self.add_fixed_in_frame_mobjects(s2_text)
+ self.add_fixed_in_frame_mobjects(s3_text)
+ self.wait(2)
+ self.play(FadeOut(s1_text))
+ self.play(FadeOut(s2_text))
+ self.play(FadeOut(s3_text))
+ self.wait(1)
+ self.play(Write(f))
+ self.play(Write(d))
+ self.play(Write(r))
+ self.wait(2)
+ self.play(ReplacementTransform(f,s),ReplacementTransform(d,d2),ReplacementTransform(r,r2))
+ self.wait(2)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.gif
new file mode 100644
index 0000000..6d5a67a
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py
new file mode 100644
index 0000000..02576d9
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py
@@ -0,0 +1,85 @@
+from manimlib.imports import*
+import math as m
+
+#---- tangent plane approximation visualization
+class ApproximationScene(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes().scale(1.2).fade(0.7)
+ label_x= TextMobject("$x$").shift([5.4,-0.5,0]).fade(0.7) #---- x axis
+ label_y= TextMobject("$y$").shift([-0.5,5.2,0]).rotate(-4.5).fade(0.7) #---- y axis
+
+ #---- graph of the function
+ s = ParametricSurface(
+ lambda u, v: np.array([
+ 1.5*np.cos(u)*np.cos(v),
+ 1.5*np.cos(u)*np.sin(v),
+ 1.5*np.sin(u)
+ ]),u_min=0,u_max=PI,v_min=PI,v_max=2*PI,checkerboard_colors=[BLUE_B,BLUE_C,BLUE_D,BLUE_E]).shift([0,1,2.4]).scale(1.3)
+
+ d1 = Dot([0.2,2.01,2.24],color = '#800000').rotate(1.1,LEFT) #---- point(x_0,y_0)
+ d1_copy = Dot([0.2,2.01,0],color = '#800000') #---- projection of point(x_0,y_0) on x-y plane
+
+ d1_text = TextMobject("$f(x_0,y_0)$",color=ORANGE).scale(0.5).shift([0.2,2.01,2.3])
+ d1_copy_text = TextMobject("$(x_0,y_0)$",color=ORANGE).scale(0.5).shift([0.2,2.01,0],4.1*DOWN)
+
+ d2 = Dot([2,2.6,3.5],color = '#800000').rotate(1,LEFT) #---- point(x,y)
+ d2_copy = Dot([2,2.6,0],color = '#800000') #---- projection of point(x,y) on x-y plane
+
+ d2_text = TextMobject("$f(x,y)$",color=ORANGE).scale(0.5).shift([0.8,1.4,1.5])
+ d2_copy_text = TextMobject("$(x,y)$",color=ORANGE).scale(0.5).shift([0.8,1.4,0],2.4*DOWN)
+
+ l1 = Line([0.2,2.01,2.21],[0.2,2.01,0],color= YELLOW).fade(0.2)
+ l2 = Line([2,2.6,3.4],[2,2.6,0],color= YELLOW).fade(0.2)
+
+ t_plane = Rectangle(color = PURPLE, fill_opacity=0.3).scale(0.6).rotate(m.radians(45),LEFT).shift([1.1,2.5,3.1]) #---- tangent plane
+ t_text= TextMobject("Tangent Plane",color = PINK).scale(0.5).shift(0.3*RIGHT+2.6*UP).rotate(math.radians(5),LEFT)
+
+ a1 = Line([0.2,2.01,0],[2,2.6,0],color ="#00FF7F")
+ a_x = Line([0.2,2.01,0],[2,2.01,0],color ="#9400D3")
+ a_y = Line([0.2,2.01,0],[0.2,2.6,0],color ="#8B4513")
+ a2 = Line([2,2.01,0],[2,2.6,0])
+ a3 = Line([0.2,2.6,0],[2,2.6,0])
+
+ ax_text = TextMobject("$f_x (x_0 , y_0 )(x – x_0 ) $").scale(0.5).shift(DOWN+0.8*LEFT).rotate(0.4)
+ ay_text = TextMobject("$ f_y (x_0 , y_0 )(y – y_0 ) $").scale(0.5).shift(0.8*DOWN+2.7*RIGHT).rotate(-0.6)
+ a1_text = TextMobject("$f_x (x_0 , y_0 )(x – x_0 ) + f_y (x_0 , y_0 )(y – y_0 )$ ").scale(0.4).rotate(0.7).shift(1.7*DOWN+0.6*RIGHT)
+
+ lines = VGroup(a1,a_y,a_x,a2,a3,d1_copy,d2_copy)
+
+
+ self.set_camera_orientation(phi = 60 * DEGREES, theta = 55 * DEGREES)
+ self.wait(1)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.play(Write(s))
+ self.wait(1)
+ self.play(Write(d2))
+ self.add_fixed_in_frame_mobjects(d1_text)
+ self.wait(1)
+ self.play(Write(t_plane))
+ self.add_fixed_in_frame_mobjects(t_text)
+ self.wait(1)
+ self.play(Write(d1))
+ self.add_fixed_in_frame_mobjects(d2_text)
+ self.wait(1)
+ self.play(Write(l1),Write(d1_copy))
+ self.add_fixed_in_frame_mobjects(d2_copy_text)
+ self.wait(1)
+ self.play(Write(l2),Write(d2_copy))
+ self.add_fixed_in_frame_mobjects(d1_copy_text)
+ self.wait(2)
+ self.play(FadeOut(d1_text),FadeOut(d1_copy_text),FadeOut(d2_text),FadeOut(d2_copy_text),FadeOut(t_text))
+ self.wait(1)
+ self.play(Write(a1),Write(a_x),Write(a_y),Write(a2),Write(a3))
+ self.wait(1)
+ self.play(FadeOut(s),FadeOut(d1),FadeOut(d2),FadeOut(l1),FadeOut(l2),FadeOut(t_plane),FadeOut(label_x),FadeOut(label_y))
+ self.wait(1)
+ lines.scale(2)
+ axes.scale(1.5)
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(ax_text)
+ self.add_fixed_in_frame_mobjects(ay_text)
+ self.add_fixed_in_frame_mobjects(a1_text)
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file3_Non_Differentiable_Function.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file3_Non_Differentiable_Function.gif
new file mode 100644
index 0000000..7581a33
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file3_Non_Differentiable_Function.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file3_Non_Differentiable_Function.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file3_Non_Differentiable_Function.py
new file mode 100644
index 0000000..79d0948
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file3_Non_Differentiable_Function.py
@@ -0,0 +1,47 @@
+from manimlib.imports import*
+import math
+
+#---- tangent plane does not exists for f(x,y): sqrt(x**2+y**2) at origin
+
+class TangenttoSurface(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes().rotate(2.3)
+ axes2 = ThreeDAxes().scale(2).rotate(2.3).shift([0,0,1.3])
+
+ #----f(x,y): sqrt(x**2+y**2)
+ p = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -math.sqrt(u**2+v**2)
+ ]),v_min = -1,v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [RED_C,TEAL_D],
+ resolution = (20, 20)).scale(1)
+
+ #----size increased of f(x,y): sqrt(x**2+y**2)
+ p2 = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -math.sqrt(u**2+v**2)
+ ]),v_min = -1,v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [RED_C,TEAL_D],
+ resolution = (20, 20)).scale(3).shift([0,0,0])
+
+ self.set_camera_orientation(phi = 75 * DEGREES,theta = 40*DEGREES)
+
+ d = Dot([0,0,0],color = '#800000') #---- critical point
+ d2 = Dot([0,0,1.5],color = '#800000').scale(2) #---- size increased of critical point
+
+ f_text = TextMobject("$f$ is not differentiable at origin,because the surface").scale(0.5).to_corner(UL)
+ f2_text = TextMobject("is not flat when zoomed in at the origin.").scale(0.5).to_corner(UL).shift(0.5*DOWN)
+
+ self.add(axes)
+ self.wait(1)
+ self.play(Write(p),Write(d))
+ self.wait(1)
+ self.move_camera(phi = 50 * DEGREES,theta = 40*DEGREES)
+ self.wait(1)
+ self.play(ReplacementTransform(axes,axes2),ReplacementTransform(p,p2),ReplacementTransform(d,d2))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(f_text)
+ self.add_fixed_in_frame_mobjects(f2_text)
+ self.wait(2)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.gif
new file mode 100644
index 0000000..3fe7992
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.py
new file mode 100644
index 0000000..d129213
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.py
@@ -0,0 +1,62 @@
+from manimlib.imports import*
+
+class TangenttoSurface(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes()
+
+ #----graph of first function f(x,y) = -x**2-y**2
+ f = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -u**2-v**2
+ ]),v_min = -1, v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [YELLOW_D, YELLOW_E],
+ resolution = (20, 20)).scale(1)
+ f_text = TextMobject("Tangent plane at relative maxima").to_corner(UL).scale(0.5)
+
+ #----graph of second function f(x,y) = -x**2+y**2
+ f2 = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -u**2+v**2
+ ]),v_min = -1, v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [RED_D, RED_E],
+ resolution = (20, 20)).scale(1)
+ f2_text = TextMobject("Tangent plane at saddle point").to_corner(UL).scale(0.5)
+
+ #----graph of third function f(x,y) = x**2+y**2
+ f3 = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u**2+v**2
+ ]),v_min = -1, v_max = 1, u_min = -1, u_max = 1, checkerboard_colors = [GREEN_D, GREEN_E],
+ resolution = (20, 20)).scale(1)
+ f3_text = TextMobject("Tangent plane at relative minima").to_corner(UL).scale(0.5)
+
+ self.set_camera_orientation(phi = 75 * DEGREES, theta = -45 * DEGREES )
+ d = Dot(np.array([0,0,0]), color = '#800000') #---- critical point
+
+ r = Rectangle(height = 2,breadth = 1,color = PURPLE).scale(0.5)
+
+ self.begin_ambient_camera_rotation(rate = 0.3)
+ self.add(axes)
+ self.play(Write(f),Write(d))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(f_text)
+ self.play(ShowCreation(r))
+ self.wait(1)
+ self.play(FadeOut(r),FadeOut(f),FadeOut(d),FadeOut(f_text))
+ self.wait(1)
+ self.play(Write(f2),Write(d))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(f2_text)
+ self.play(ShowCreation(r))
+ self.wait(1)
+ self.play(FadeOut(r),FadeOut(f2),FadeOut(d),FadeOut(f2_text))
+ self.wait(1)
+ self.play(Write(f3),Write(d))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(f3_text)
+ self.play(ShowCreation(r))
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/README.md b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/README.md
new file mode 100644
index 0000000..96b32bf
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/README.md
@@ -0,0 +1,27 @@
+<h1><div align=”center”><b>SubTopic: The Second Derivative Test</b></h1></div>
+<br/></br>
+
+<tab>file1_Second_order_partial_derivatives
+
+![file1_Second_order_partial_derivatives](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file2_Nondegenerate_Hessian_Matrix
+
+![file2_Nondegenerate_Hessian_Matrix](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Nondegenerate_Hessian_Matrix.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file3_Degenerate_Hessian_Matrix
+
+![file3_Degenerate_Hessian_Matrix](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Degenerate_Hessian_Matrix.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file4_Contour_Diagram
+
+![file4_Contour_Diagram](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.gif?raw=true)
+<br/></br>
+<br/></br>
+
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.gif
new file mode 100644
index 0000000..3471e4d
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.py
new file mode 100644
index 0000000..84052cc
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.py
@@ -0,0 +1,78 @@
+from manimlib.imports import*
+
+#---- graphs of second-order partial derivatives of a function
+class SurfacesAnimation(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes()
+ x_label = TextMobject('$x$').shift([5,0.5,0]) #---- x axis
+ y_label = TextMobject('$y$').shift([0.5,4,0]).rotate(-4.5) #---- y axis
+
+ #---- surface of function: f(x,y) = (x^2+y^2)^2
+ surface_f = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ ((u**2)+(v**2))**2
+ ]),v_min=-1,v_max=1,u_min=-1,u_max=1,checkerboard_colors=[GREEN_D, GREEN_E]).scale(1)
+
+ #---- surface of second-order partial derivative f_xx
+ surface_fxx = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ (3*u**2)+(v**2)
+ ]),v_min=-1,v_max=1,u_min=-1,u_max=1,checkerboard_colors=[YELLOW_D, YELLOW_E]).shift([0,0,0]).scale(0.6)
+
+ #---- surface of second-order partial derivative f_yy
+ surface_fyy = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ (u**2)+(3*v**2)
+ ]),v_min=-1,v_max=1,u_min=-1,u_max=1,checkerboard_colors=[PURPLE_D, PURPLE_E]).scale(0.6).shift([0,0,0])
+
+ #---- surface of second-order partial derivative f_xy = f_yx
+ surface_fxy = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ 8*u*v
+ ]),v_min=-1,v_max=1,u_min=-1,u_max=1,checkerboard_colors=[TEAL_D, TEAL_E]).scale(0.6)
+
+ f_text= TextMobject("$f(x,y) = (x^2+y^2)^2$",color = GREEN).scale(0.7).to_corner(UL)
+
+ fxx_text= TextMobject("$f_{xx} = 12x^2+4y^2$ (Concavity along x axis)",color = YELLOW).scale(0.5).to_corner(UL)
+
+ fyy_text= TextMobject("$f_{yy} = 4x^2+12y^2$(Concavity along y axis)",color = PURPLE).scale(0.5).to_corner(UL)
+
+ fxy_text= TextMobject("$f_{xy} = f_{yx} = 8xy$ (Twisting of the function)",color = TEAL).scale(0.5).to_corner(UL)
+
+
+ self.set_camera_orientation(phi = 40 * DEGREES, theta = 45 * DEGREES)
+ self.begin_ambient_camera_rotation(rate = 0.1)
+ self.add_fixed_in_frame_mobjects(f_text)
+ self.add(axes)
+ self.add(x_label)
+ self.add(y_label)
+ self.wait(1)
+ self.play(Write(surface_f))
+ self.wait(2)
+ self.play(FadeOut(f_text))
+
+
+ self.play(ReplacementTransform(surface_f,surface_fxx))
+
+ self.add_fixed_in_frame_mobjects(fxx_text)
+ self.wait(2)
+ self.play(FadeOut(fxx_text))
+
+ self.play(ReplacementTransform(surface_fxx,surface_fyy))
+ self.add_fixed_in_frame_mobjects(fyy_text)
+ self.wait(2)
+ self.play(FadeOut(fyy_text))
+
+ self.play(ReplacementTransform(surface_fyy,surface_fxy))
+ self.move_camera(phi = 35 * DEGREES, theta = 80 * DEGREES)
+ self.add_fixed_in_frame_mobjects(fxy_text)
+ self.wait(2)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Nondegenerate_Hessian_Matrix.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Nondegenerate_Hessian_Matrix.gif
new file mode 100644
index 0000000..0d58b4f
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Nondegenerate_Hessian_Matrix.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Nondegenerate_Hessian_Matrix.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Nondegenerate_Hessian_Matrix.py
new file mode 100644
index 0000000..32c1559
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Nondegenerate_Hessian_Matrix.py
@@ -0,0 +1,158 @@
+from manimlib.imports import*
+import math as m
+
+class Minima(ThreeDScene):
+ def construct(self):
+
+ heading = TextMobject("Nondegenerate Hessian Matrix",color = BLUE)
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.3,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.3,5.5,0]).rotate(-4.5) #---- y axis
+
+ h_text = TextMobject("Case 1: $\\frac{\\partial^2 f}{\\partial x^2}>0$ and $\\frac{\\partial^2 f}{\\partial y^2}>0$").scale(1)
+
+ #---- determiniant of Hessian Matrix
+ hessian_surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -0.5*m.exp(-u**2-v**2)
+ ]),u_min = -PI, u_max = PI, v_min = -PI, v_max =PI).set_color(TEAL).shift([0,0,0]).scale(1).fade(0.2)
+
+ det_text= TextMobject("$det \\hspace{1mm} H = (\\frac{\\partial^2 f}{\\partial x^2})(\\frac{\\partial^2 f}{\\partial y^2})-(\\frac{\\partial^2 f}{\\partial x \\partial y})^2 $").to_corner(UL).scale(0.7)
+
+ #---- function f(x,y)
+ f_surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u**2+v**2
+ ]),u_min = -1.3, u_max = 1.3, v_min = -1.3, v_max = 1.3).set_color(TEAL).shift([0,0,-0.5])
+
+ f_text= TextMobject("surface of the function").to_corner(UL).scale(0.8)
+
+ d = Dot(color = "#800000").shift([0,0,-0.52]) #---- critical point
+
+ self.set_camera_orientation(phi = 75*DEGREES, theta = 40*DEGREES)
+ self.add_fixed_in_frame_mobjects(heading)
+ self.wait(1)
+ self.play(FadeOut(heading))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(h_text)
+ self.wait(1)
+ self.play(FadeOut(h_text))
+ self.wait(1)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.play(Write(hessian_surface))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(det_text)
+ self.move_camera(phi = 90*DEGREES, theta= 60*DEGREES)
+ self.play(Write(d))
+ self.wait(1)
+ self.play(FadeOut(det_text),ReplacementTransform(hessian_surface,f_surface))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(f_text)
+ self.wait(1)
+ self.play(FadeOut(f_text),FadeOut(f_surface),FadeOut(axes),FadeOut(label_x),FadeOut(label_y),FadeOut(d))
+
+class Maxima(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.3,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.3,5.5,0]).rotate(-4.5) #---- y axis
+
+ h_text = TextMobject("Case 2: $\\frac{\\partial^2 f}{\\partial x^2}<0$ and $\\frac{\\partial^2 f}{\\partial y^2}<0$").scale(1)
+
+ #---- determiniant of Hessian Matrix
+ hessian_surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ 0.5*m.exp(-u**2-v**2)
+ ]),u_min = -PI, u_max = PI, v_min = -PI, v_max =PI).set_color(TEAL).shift([0,0,0]).scale(1).fade(0.2)
+
+ det_text= TextMobject("$det \\hspace{1mm} H = (\\frac{\\partial^2 f}{\\partial x^2})(\\frac{\\partial^2 f}{\\partial y^2})-(\\frac{\\partial^2 f}{\\partial x \\partial y})^2 $").to_corner(UL).scale(0.7)
+
+ #---- function g(x,y)
+ g_surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -u**2-v**2
+ ]),u_min = -1.3, u_max = 1.3, v_min = -1.3, v_max = 1.3).set_color(TEAL).shift([0,0,0.5])
+
+ g_text= TextMobject("surface of the function").to_corner(UL).scale(0.8)
+
+ d = Dot(color = "#800000").shift([0,0,0.5]) #---- critical point
+
+ self.set_camera_orientation(phi = 75*DEGREES, theta = 40*DEGREES)
+ self.add_fixed_in_frame_mobjects(h_text)
+ self.wait(1)
+ self.play(FadeOut(h_text))
+ self.wait(1)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.play(Write(hessian_surface))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(det_text)
+ self.play(Write(d))
+ self.wait(1)
+ self.play(FadeOut(det_text),ReplacementTransform(hessian_surface,g_surface))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(g_text)
+ self.wait(1)
+ self.play(FadeOut(g_text),FadeOut(g_surface),FadeOut(axes),FadeOut(label_x),FadeOut(label_y),FadeOut(d))
+
+class SaddlePoint(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.3,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.3,5.5,0]).rotate(-4.5) #---- y axis
+
+ h_text = TextMobject("Case 3: $\\frac{\\partial^2 f}{\\partial x^2}$ and $\\frac{\\partial^2 f}{\\partial y^2}$ have opposite signs").scale(1)
+
+ #---- determiniant of Hessian Matrix
+ hessian_surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ m.exp(0.5*u**2-0.5*v**2)
+ ]),u_min = -1.2, u_max = 1.2, v_min = -2.5, v_max = 2.5).set_color(TEAL).shift([0,0,-1]).scale(1).fade(0.2)
+
+ det_text= TextMobject("$det \\hspace{1mm} H = (\\frac{\\partial^2 f}{\\partial x^2})(\\frac{\\partial^2 f}{\\partial y^2})-(\\frac{\\partial^2 f}{\\partial x \\partial y})^2 $").to_corner(UL).scale(0.7)
+
+ #---- function p(x,y)
+ p_surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u**2-v**2
+ ]),u_min = -1, u_max = 1, v_min = -1, v_max =1).set_color(TEAL).shift([0,0,0]).scale(2)
+
+ p_text= TextMobject("surface of the function").to_corner(UL).scale(0.8)
+
+ d = Dot(color = "#800000").shift([0,0,0]) #---- critical point
+
+ self.set_camera_orientation(phi = 80*DEGREES, theta = 60*DEGREES)
+ self.add_fixed_in_frame_mobjects(h_text)
+ self.wait(1)
+ self.play(FadeOut(h_text))
+ self.wait(1)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.wait(1)
+ self.play(Write(hessian_surface))
+ self.play(Write(d))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(det_text)
+ self.wait(2)
+ self.play(FadeOut(det_text),ReplacementTransform(hessian_surface,p_surface))
+ self.add_fixed_in_frame_mobjects(p_text)
+ self.wait(2)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Degenerate_Hessian_Matrix.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Degenerate_Hessian_Matrix.gif
new file mode 100644
index 0000000..5aae300
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Degenerate_Hessian_Matrix.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Degenerate_Hessian_Matrix.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Degenerate_Hessian_Matrix.py
new file mode 100644
index 0000000..9310553
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Degenerate_Hessian_Matrix.py
@@ -0,0 +1,45 @@
+from manimlib.imports import*
+import math as m
+
+class DegenerateHessian(ThreeDScene):
+ def construct(self):
+
+ heading = TextMobject("Degenerate Hessian Matrix",color = BLUE)
+
+ h_text = TextMobject("For $det \\hspace{1mm} H = 0$, the surface of the function at the critical point would be flat.").scale(0.7)
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.3,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.3,5.5,0]).rotate(-4.5) #---- y axis
+
+ #---- function f(x,y)
+ f_surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ -u**4-v**4
+ ]),u_min = -0.8, u_max = 0.8, v_min = -0.8, v_max = 0.8).set_color(TEAL).shift([0,0,-0.5]).scale(2)
+
+ f_text= TextMobject("surface of the function").to_corner(UL).scale(0.5)
+
+ d = Dot(color = "#800000").shift([0,0,-0.5]) #---- critical point
+ plane = Square(color = YELLOW,fill_opacity= 0.2).shift([0,0,-0.5]).scale(1.3)
+
+ self.set_camera_orientation(phi = 70*DEGREES, theta = 45*DEGREES)
+ self.add_fixed_in_frame_mobjects(heading)
+ self.wait(1)
+ self.play(FadeOut(heading))
+ self.add_fixed_in_frame_mobjects(h_text)
+ self.wait(2)
+ self.play(FadeOut(h_text))
+ self.wait(1)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.play(Write(f_surface))
+ self.add_fixed_in_frame_mobjects(f_text)
+ self.wait(1)
+ self.play(Write(d))
+ self.wait(1)
+ self.play(Write(plane))
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.gif
new file mode 100644
index 0000000..41068e2
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.py
new file mode 100644
index 0000000..d3084e2
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.py
@@ -0,0 +1,120 @@
+from manimlib.imports import*
+
+#---- contour diagram animation
+class ContourDiagram(ThreeDScene):
+ def construct(self):
+
+ heading = TextMobject("CONTOUR DIAGRAM", color = YELLOW).scale(1)
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.5,0]) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5) #---- y axis
+
+ #---- surface of a paraboloid
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ np.cos(v)*u,
+ np.sin(v)*u,
+ u**2
+ ]),v_min = -2, v_max = 2, u_min = -2, u_max = 2, checkerboard_colors = [GREEN_B,GREEN_C,GREEN_D,GREEN_E]).shift([0,0,0]).scale(0.5)
+
+ #---- first contour projection
+ contour1 = ParametricSurface(
+ lambda u, v: np.array([
+ np.cos(TAU * v),
+ np.sin(TAU * v),
+ 2*(1 - 2.5*u)
+ ])).fade(0.5).scale(0.21).shift([0,0,1.01])
+
+ #---- first contour line
+ c_1 = Circle(color = BLUE).scale(0.21).shift([0,0,0]).rotate(0.1,DOWN)
+
+ #-------------------------------------------------
+
+ #---- second contour projection
+ contour2 = ParametricSurface(
+ lambda u, v: np.array([
+ np.cos(TAU * v),
+ np.sin(TAU * v),
+ 2*(1 - 1.6*u)
+ ])).fade(0.5).scale(0.41).shift([0,0,0.3]).set_color(RED)
+
+ #---- second contour line
+ c_2 = Circle(color = RED).scale(0.41).shift([0,0,0]).rotate(0.1,DOWN)
+
+ #-------------------------------------------------
+
+ #---- third contour projection
+ contour3 = ParametricSurface(
+ lambda u, v: np.array([
+ np.cos(TAU * v),
+ np.sin(TAU * v),
+ 2*(1 - 1.5*u)
+ ])).fade(0.5).scale(0.61).shift([0,0,0.4]).set_color(YELLOW)
+
+ #---- third contour line
+ c_3 = Circle(color = YELLOW).scale(0.61).shift([0,0,0])
+
+ #-------------------------------------------------
+
+ #---- fourth contour projection
+ contour4 = ParametricSurface(
+ lambda u, v: np.array([
+ np.cos(TAU * v),
+ np.sin(TAU * v),
+ 2*(1 - 1.5*u)
+ ])).fade(0.7).scale(0.81).shift([0,0,0.7]).set_color(PINK)
+
+ #---- fourth contour line
+ c_4 = Circle(color = PINK).scale(0.81).shift([0,0,0])
+
+ #-------------------------------------------------
+
+ #---- fifth contour projection
+ contour5 = ParametricSurface(
+ lambda u, v: np.array([
+ np.cos(TAU * v),
+ np.sin(TAU * v),
+ 2*(1 - 1.5*u)
+ ])).fade(0.7).scale(1.01).shift([0,0,1]).set_color(PURPLE)
+
+ #---- fifth contour line
+ c_5 = Circle(color = PURPLE).scale(1.01).shift([0,0,0])
+
+ c_text= TextMobject("Contour Lines").scale(0.5).shift(2*DOWN)
+ s = Square().scale(1.3)
+
+ self.set_camera_orientation(phi = 75 * DEGREES, theta = 10 * DEGREES)
+ self.add_fixed_in_frame_mobjects(heading)
+ self.wait(1)
+ self.play(FadeOut(heading))
+ self.wait(1)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.play(Write(surface))
+ self.wait(1)
+ self.add(contour1)
+ self.wait(1)
+ self.play(Write(c_1))
+ self.play(ReplacementTransform(contour1,contour2))
+ self.wait(1)
+ self.play(Write(c_2))
+ self.play(ReplacementTransform(contour2,contour3))
+ self.wait(1)
+ self.play(Write(c_3))
+ self.play(ReplacementTransform(contour3,contour4))
+ self.wait(1)
+ self.play(Write(c_4))
+ self.play(ReplacementTransform(contour4,contour5))
+ self.wait(1)
+ self.play(Write(c_5))
+ self.wait(1)
+ self.play(FadeOut(contour5),FadeOut(axes),FadeOut(label_x),FadeOut(label_y),FadeOut(surface),FadeOut(contour5),FadeOut(contour4),FadeOut(contour3),FadeOut(contour2),FadeOut(contour1))
+ self.wait(1)
+ self.move_camera(phi=0 * DEGREES,theta= 90*DEGREES)
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(c_text)
+ self.wait(1)
+ self.play(ShowCreation(s),FadeOut(c_text))
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/README.md b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/README.md
new file mode 100644
index 0000000..ce4da11
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/README.md
@@ -0,0 +1,34 @@
+<h1><div align=”center”><b>SubTopic: Total Differential</b></h1></div>
+<br/></br>
+
+<tab>file1_Visualization_of_dz
+
+![file1_Visualization_of_dz](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file2_Differentials
+
+![file2_Differentials](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.gif?raw=true)
+
+<br/></br>
+<br/></br>
+
+<tab>file3_Total_differential_of_z
+
+![file3_Total_differential_of_z](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file4_total_differential_change
+
+![file4_total_differential_change](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file4_total_differential_change.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file5_Total_differential_approximation
+
+ ![file5_Total_differential_approximation](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.gif?raw=true)
+
+<br/></br>
+<br/></br>
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.gif
new file mode 100644
index 0000000..2e148af
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.py
new file mode 100644
index 0000000..1fdd0b9
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.py
@@ -0,0 +1,59 @@
+from manimlib.imports import*
+
+#---- visualization of total differential dz between two points lying on the surface of the function
+class differentialdz(ThreeDScene):
+
+ def construct(self):
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.5,0]).fade(0.4) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5).fade(0.4) #---- y axis
+
+ #---- surface of the funtion f(x,y)
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u**2+v**2
+ ]),u_min=-1,u_max=1, v_min=-1,v_max=1).set_color("#FF69B4").fade(0.6).scale(2).shift(3*UP+1*LEFT)
+
+ d = Dot([1.4,1.75,1],color = '#00FFFF').rotate(1.571,UP) #---- point on the surface
+ d2 = Dot([2,2,1],color = '#00FFFF').rotate(1.571,UP) #---- point on the surface
+
+ p1 = TextMobject("$P_1$",color ='#ADFF2F').scale(0.6).shift(2*RIGHT+1*UP)
+ p2 = TextMobject("$P_2$",color = '#ADFF2F').scale(0.6).shift(2.6*RIGHT+0.9*UP)
+
+ l = DashedLine(color = '#800000').rotate(1.571,UP).scale(1).shift(1.7*UP+1.6*RIGHT)
+ l2 = DashedLine(color = '#800000').rotate(1.571,UP).scale(0.8).shift(2.26*UP+1.2*RIGHT)
+
+ l_text = TextMobject("$(x_1,y_1)$",color = '#ADFF2F').scale(0.6).shift(2*RIGHT+1.6*DOWN)
+ l2_text = TextMobject("$(x_2,y_2)$",color = '#ADFF2F').scale(0.6).shift(2.7*RIGHT+1.2*DOWN)
+
+ a = Arrow(color = '#FFFACD').scale(0.7).rotate(1.38,RIGHT).shift(2.5*LEFT+3.1*UP)
+
+ a_text = TextMobject("$dz$",color='#800000').scale(0.5).shift(2.3*RIGHT+0.5*UP)
+
+ plane = Rectangle(color = '#E6E6FA',fill_opacity = 1).scale(3).shift(1*RIGHT+3*UP).fade(0.9)
+
+ label = TextMobject("$z = f(x,y)$").scale(0.6).shift(3.5*RIGHT+1.8*UP)
+
+ self.set_camera_orientation(phi=75*DEGREES,theta=-10*DEGREES)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.wait(1)
+ self.play(Write(plane))
+ self.play(Write(surface))
+ self.add_fixed_in_frame_mobjects(label)
+ self.wait(1)
+ self.play(ShowCreation(l),ShowCreation(l2),Write(d),Write(d2))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(p1)
+ self.add_fixed_in_frame_mobjects(p2)
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(l_text)
+ self.add_fixed_in_frame_mobjects(l2_text)
+ self.play(ShowCreation(a))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(a_text)
+ self.wait(2)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.gif
new file mode 100644
index 0000000..6baf271
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.py
new file mode 100644
index 0000000..1025210
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.py
@@ -0,0 +1,77 @@
+from manimlib.imports import*
+
+#---- visualization of the differentials along the axes
+class differentials(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.3,0]).fade(0.4) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5).fade(0.4) #---- y axis
+
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u**2+v**2
+ ]),u_min=-1,u_max=1, v_min=-1,v_max=1).set_color("#FF69B4").shift([0,2.5,0.3]).scale(1.2) #----surface z = f(x,y)
+
+
+
+ plane = Rectangle(color = '#E6E6FA',fill_opacity = 1).scale(3).shift(-1*RIGHT+3*UP).fade(0.9)
+
+ d = Dot([1,2,1],color = '#9400D3').rotate(1.571,UP)
+ d2 = Dot([2,2.9,1],color = '#9400D3').rotate(1.571,UP)
+
+ p1 = TextMobject("$P_1$",color ='#ADFF2F').scale(0.6).shift(2*RIGHT+1*UP)
+ p2 = TextMobject("$P_2$",color = '#ADFF2F').scale(0.6).shift(2.6*RIGHT+0.4*UP)
+
+
+ l1 = DashedLine(color = '#00BFFF').scale(1.6).shift(3.5*UP+3.25*LEFT).rotate(1.571)
+ l2 = DashedLine(color = '#00BFFF').scale(1).shift(4*UP+2*LEFT).rotate(1.571)
+
+ label_dz= TextMobject("$dz$").scale(0.4).shift(5.3*RIGHT+0.4*UP)
+
+
+ l3 = Line(color = '#FFDAB9').scale(0.8).shift(1.95*UP+0.7*RIGHT).rotate(1.571,DOWN).fade(0.2)
+ l4 = Line(color = '#FFDAB9').scale(0.6).shift(2.86*UP+0.9*RIGHT).rotate(1.571,DOWN).fade(0.2)
+
+ line_y1 = DashedLine(color = '#00BFFF').scale(1.3).shift(0.82*UP+3.25*RIGHT).rotate(1.571)
+ line_y2 = DashedLine(color = '#00BFFF').scale(1.7).shift(1.2*UP+2.8*RIGHT).rotate(1.571)
+
+ label_dy= TextMobject("$dy$").scale(0.6).shift(3*RIGHT+0.8*DOWN).rotate(math.radians(90))
+
+ line_x1 = DashedLine(color = '#00BFFF').scale(1.5).shift(2.2*UP+1.6*RIGHT).rotate(1.571,RIGHT)
+ line_x2 = DashedLine(color = '#00BFFF').scale(1.2).shift(2.9*UP+1.6*RIGHT).rotate(1.571,RIGHT)
+
+ label_dx= TextMobject("$dx$").scale(0.4).shift(-0.4*UP+2.5*RIGHT)
+
+ label = TextMobject("$f(x,y)$").scale(0.6).shift(4*RIGHT+3*UP)
+
+
+ self.set_camera_orientation(phi=75*DEGREES,theta=10*DEGREES)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.play(Write(plane))
+ self.play(Write(surface))
+ self.add_fixed_in_frame_mobjects(label)
+ self.wait(1)
+ self.play(Write(d),Write(d2))
+ self.add_fixed_in_frame_mobjects(p1)
+ self.add_fixed_in_frame_mobjects(p2)
+ self.wait(1)
+ self.play(Write(l1))
+ self.play(Write(l2))
+ self.add_fixed_in_frame_mobjects(label_dz)
+ self.wait(1)
+ self.play(Write(l3))
+ self.play(Write(l4))
+ self.wait(1)
+ self.play(Write(line_y1))
+ self.play(Write(line_y2))
+ self.play(ShowCreation(label_dy))
+ self.wait(1)
+ self.play(Write(line_x1))
+ self.play(Write(line_x2))
+ self.add_fixed_in_frame_mobjects(label_dx)
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.gif
new file mode 100644
index 0000000..a54d2da
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.py
new file mode 100644
index 0000000..b8d6f96
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.py
@@ -0,0 +1,100 @@
+from manimlib.imports import*
+
+#---- visualization of total differential definition
+class totaldifferential(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes().fade(0.5)
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u**2+v**2
+ ]),u_min=-1,u_max=1, v_min=-1,v_max=1).set_color("#FF69B4").fade(0.6).shift([1,0.8,1.5]).scale(2)
+
+ plane = Rectangle(color = '#E6E6FA',fill_opacity = 1).scale(3).shift(-1*RIGHT+3*UP).fade(0.9)
+ label_x = TextMobject("$x$").shift(5*RIGHT+0.4*DOWN).rotate(1.571)
+ label_y = TextMobject("$y$").shift(0.3*DOWN+5.6*RIGHT).scale(0.5)
+ label_z = TextMobject("$z$").shift(3.5*UP+0.2*LEFT).scale(0.5)
+
+ s1 = Square(color = '#00FF00',fill_opacity=0.4).shift([1,1,0])
+ s2 = Square(color = '#00FF00',fill_opacity=0.4).shift([1,1,3]).scale(0.95)
+
+ l1 = Line([2,0,3],[2,0,0],color = '#FFFACD')
+ l2 = Line([0,2,3],[0,2,0],color = '#FFFACD')
+ l3 = Line([2,1.95,3],[2,2,0],color = '#FFFACD')
+
+ d1 = Dot([2,0,1.5],color = '#FFD700').rotate(1.571,UP)
+ d1_text = TextMobject("$P1$").scale(0.4).shift(1.2*LEFT+1.1*UP)
+
+ d2 = Dot([0,2,3],color = '#FFD700').rotate(1.571,UP)
+ d2_text = TextMobject("$P2$").scale(0.4).shift(2.3*RIGHT+3.1*UP)
+
+ d3 = Dot([2,2,2],color = '#FFD700').rotate(1.571,UP)
+ d3_text = TextMobject("$Q$").scale(0.4).shift([1.6,-1,0]+2.5*UP)
+
+ s3 = Square().shift([1,1,1.5]).scale(0.95)
+ s4 = Square().shift([1,1,2]).scale(0.95)
+
+ m1_line = DashedLine([2,0,1.5],[2,2,2],color = '#87CEEB')
+ m2_line = DashedLine([2,2,2],[0,2,3],color = '#87CEEB')
+
+ dx_line = Line([2,2,0],[4,2,0],color = '#00FF7F')
+ dy_line = Line([2,2,0],[2,4,0],color = '#00FF7F')
+
+ dx = DashedLine([3.5,0,0],[3.5,2,0],color = '#87CEEB')
+ dy = DashedLine([0,3.5,0],[2,3.5,0],color = '#87CEEB')
+
+ dx_text = TextMobject("$dx$").scale(0.8).shift([4,1,0]).rotate(1.571)
+ dy_text = TextMobject("$dy$").scale(0.8).shift([1,3.8,0]).rotate(math.radians(180))
+
+ parx_line = Line([0,2,1.5],[0,5,1.5],color = '#00FF7F')
+ parm_line = Line([0,2,2],[0,5,2],color = '#00FF7F')
+ pary_line = Line([0,2.1,3],[0,5,3],color = '#00FF7F')
+
+ delx = DashedLine([0,4,2],[0,4,1.5],color = '#F0F8FF')
+ dely = DashedLine([0,4,3],[0,4,2],color = '#FAEBD7')
+
+ dely_text = TextMobject("$\\frac{\\partial z}{\\partial y}dy$").shift(4.6*RIGHT+2.3*UP).scale(0.4)
+ delx_text = TextMobject("$\\frac{\\partial z}{\\partial x}dx$").shift(4.6*RIGHT+1.4*UP).scale(0.4)
+
+
+ self.set_camera_orientation(phi=75*DEGREES,theta=20*DEGREES)
+ self.add(axes)
+ self.play(Write(plane))
+ self.play(ShowCreation(label_x))
+ self.add_fixed_in_frame_mobjects(label_y)
+ self.add_fixed_in_frame_mobjects(label_z)
+ self.wait(1)
+ self.play(Write(surface))
+ self.play(ShowCreation(d1))
+ self.add_fixed_in_frame_mobjects(d1_text)
+ self.play(ShowCreation(d2))
+ self.add_fixed_in_frame_mobjects(d2_text)
+ self.wait(1)
+ self.play(Write(s2))
+ self.wait(1)
+ self.play(Write(l1),Write(l2),Write(l3))
+ self.wait(1)
+ self.play(Write(s1))
+ self.wait(1)
+ self.play(FadeOut(surface))
+ self.play(ShowCreation(d3))
+ self.add_fixed_in_frame_mobjects(d3_text)
+ self.play(ShowCreation(m1_line))
+ self.play(ShowCreation(m2_line))
+ self.wait(1)
+ self.play(ShowCreation(dx_line),ShowCreation(dx),ShowCreation(dx_text))
+ self.wait(1)
+ self.play(ShowCreation(dy_line),ShowCreation(dy),ShowCreation(dy_text))
+ self.wait(2)
+ self.play(Write(s3))
+ self.play(Write(s4))
+ self.wait(1)
+ self.play(ShowCreation(parx_line),ShowCreation(parm_line),ShowCreation(pary_line))
+ self.wait(1)
+ self.play(ShowCreation(dely))
+ self.add_fixed_in_frame_mobjects(dely_text)
+ self.wait(1)
+ self.play(ShowCreation(delx))
+ self.add_fixed_in_frame_mobjects(delx_text)
+ self.wait(1)
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file4_total_differential_change.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file4_total_differential_change.gif
new file mode 100644
index 0000000..f2227a8
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file4_total_differential_change.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file4_total_differential_change.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file4_total_differential_change.py
new file mode 100644
index 0000000..78e41a2
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file4_total_differential_change.py
@@ -0,0 +1,54 @@
+from manimlib.imports import*
+
+
+class firstScene(ThreeDScene):
+
+ def construct(self):
+
+ axes = ThreeDAxes()
+
+ s = Rectangle(color = '#F08080',fill_opacity=1).fade(0.7).shift(1.9*UP+5*LEFT).scale(0.9)#----surface z = f(x,y)
+
+ s2= Rectangle(color = '#F08080',fill_opacity=1).fade(0.7).shift(2.4*UP+3.1*RIGHT).scale(0.6) #----reflection of the surface on the x-y plane
+
+ l1 = DashedLine(color = '#AFEEEE').rotate(1.571,UP).scale(1).shift(1.53*UP+1.5*RIGHT)
+ l2 = DashedLine(color = '#AFEEEE').rotate(1.571,UP).scale(1).shift(2.9*UP+1.4*RIGHT)
+ l3 = DashedLine(color = '#AFEEEE').rotate(1.571,UP).scale(1).shift(1.5*UP-1.6*RIGHT)
+ l4 = DashedLine(color = '#AFEEEE').rotate(1.571,UP).scale(1).shift(2.9*UP-1.75*RIGHT)
+
+
+ l1_text = TextMobject("$(x+\\triangle x,y)$").shift(RIGHT+1.7*DOWN).scale(0.4)
+ l2_text = TextMobject("$(x+\\triangle x,y+\\triangle y)$").shift(3*RIGHT+1.8*DOWN).scale(0.4)
+ l3_text = TextMobject("$f(x,y)$").shift(1.6*RIGHT+1.5*UP).scale(0.4)
+ l4_text = TextMobject("$(x,y+\\triangle y)$").shift(3.5*RIGHT+0.7*DOWN).scale(0.4)
+
+ label_x = TextMobject("$x$").shift(5*RIGHT+0.4*DOWN)
+ label_y = TextMobject("$y$").shift(5*UP-0.6*RIGHT)
+
+ self.add(axes)
+ self.set_camera_orientation(phi=75*DEGREES,theta=10*DEGREES)
+ self.wait(1)
+ self.play(ShowCreation(label_x),ShowCreation(label_y))
+ self.play(Write(s))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(l3_text)
+ self.wait(1)
+ self.play(Write(l3))
+ self.wait(1)
+ self.play(Write(l1))
+ self.add_fixed_in_frame_mobjects(l1_text)
+ self.wait(1)
+ self.play(Write(l2))
+ self.add_fixed_in_frame_mobjects(l2_text)
+ self.wait(1)
+ self.play(Write(l4))
+ self.add_fixed_in_frame_mobjects(l4_text)
+ self.wait(1)
+ self.play(Write(s2))
+ self.wait(1)
+
+
+
+
+
+
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.gif
new file mode 100644
index 0000000..ebbf240
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.py
new file mode 100644
index 0000000..e7b39bb
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.py
@@ -0,0 +1,52 @@
+from manimlib.imports import*
+
+#---- approximation value of function between two points using total differentials
+class approximation(ThreeDScene):
+
+ def construct(self):
+
+ axes = ThreeDAxes()
+ label_x = TextMobject("$x$").shift([5.5,-0.3,0]).fade(0.4) #---- x axis
+ label_y = TextMobject("$y$").shift([-0.5,5.5,0]).rotate(-4.5).fade(0.4) #---- y axis
+
+ surface = ParametricSurface(
+ lambda u, v: np.array([
+ np.sin(u),
+ v,
+ -u**2-v
+ ]),u_min=-1,u_max=1, v_min=-1,v_max=1).set_color("#00008B").scale(2).shift(3.8*UP+2*LEFT)
+
+ d = Dot([1.4,1.75,1],color = '#00FFFF').rotate(1.571,UP)
+ d2 = Dot([2,2,1],color = '#00FFFF').rotate(1.571,UP)
+
+ l = DashedLine(color = '#800000').rotate(1.571,UP).scale(1).shift(1.7*UP+1.6*RIGHT)
+ l2 = DashedLine(color = '#800000').rotate(1.571,UP).scale(0.8).shift(2.26*UP+1.2*RIGHT)
+
+ l_text = TextMobject("$(x_1,y_1)$",color = '#ADFF2F').scale(0.6).shift(2*RIGHT+1.6*DOWN)
+ l2_text = TextMobject("$(x_2,y_2)$",color = '#ADFF2F').scale(0.6).shift(2.7*RIGHT+1.2*DOWN)
+
+ plane = Rectangle(color = '#E6E6FA',fill_opacity = 1).scale(3).shift(1*RIGHT+3*UP).fade(0.9)
+
+ tangentplane = Rectangle(color = '#E6E6FA',fill_opacity = 1).scale(1.1).shift(2*LEFT+3.4*UP).fade(0.5).rotate(0.8,RIGHT)
+ tangentplane_text = TextMobject("Tangent Plane").scale(0.4).shift(3*RIGHT+1*UP)
+
+ label = TextMobject("$z = f(x,y)$").scale(0.6).shift(4*RIGHT+3*UP)
+
+ self.set_camera_orientation(phi=75*DEGREES,theta=-10*DEGREES)
+ self.add(axes)
+ self.add(label_x)
+ self.add(label_y)
+ self.wait(1)
+ self.play(Write(plane))
+ self.wait(1)
+ self.play(Write(surface))
+ self.add_fixed_in_frame_mobjects(label)
+ self.wait(1.5)
+ self.play(ShowCreation(l),ShowCreation(l2),Write(d),Write(d2))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(l_text)
+ self.add_fixed_in_frame_mobjects(l2_text)
+ self.wait(1)
+ self.play(Write(tangentplane))
+ self.add_fixed_in_frame_mobjects(tangentplane_text)
+ self.wait(2)