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-rw-r--r--FSF-2020/approximations-and-optimizations/Critical-Points/README.md32
-rw-r--r--FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py34
-rw-r--r--FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file3_non_differentiable_function.py30
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/README.md32
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.gif (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.gif)bin8077401 -> 8077401 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.py (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file1_Critical_Point_of_a_function.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.gif (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.gif)bin2552938 -> 2552938 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.py (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file2_Traces_and_Tangent.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.gif (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.gif)bin2198637 -> 2198637 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.py (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.gif (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.gif)bin3864765 -> 3864765 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.py (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).gif (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).gif)bin1522415 -> 1522415 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).py (renamed from FSF-2020/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.gifbin0 -> 499796 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.py53
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.gifbin0 -> 419262 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.py68
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Optimizing_function_w.r.t_one_constraint.gifbin0 -> 2177236 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Optimizing_function_w.r.t_one_constraint.py29
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.gif (renamed from FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.gif)bin827096 -> 827096 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.py (renamed from FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file1_Tangent_Plane.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.gifbin0 -> 946542 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py74
-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 -> 2513197 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.py (renamed from FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent plane_at_critical_points.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.gif (renamed from FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.gif)bin3166332 -> 3166332 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.py (renamed from FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file1_Second_order_partial_derivatives.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.gifbin0 -> 3202838 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.py (renamed from FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.gifbin0 -> 8724439 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.py (renamed from FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.gif (renamed from FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.gif)bin1150777 -> 1150777 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.py (renamed from FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file4_Contour_Diagram.py)0
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.gifbin0 -> 558983 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.py53
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.gifbin0 -> 576535 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.py72
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.gifbin0 -> 732678 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.py91
-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 -> 423652 bytes
-rw-r--r--FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.py48
46 files changed, 621 insertions, 96 deletions
diff --git a/FSF-2020/approximations-and-optimizations/Critical-Points/README.md b/FSF-2020/approximations-and-optimizations/Critical-Points/README.md
deleted file mode 100644
index f0747bb..0000000
--- a/FSF-2020/approximations-and-optimizations/Critical-Points/README.md
+++ /dev/null
@@ -1,32 +0,0 @@
-<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/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/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/approximations-and-optimizations/Critical-Points/file3_Tangent_plane_at_extrema_of_a_function.gif?raw=true)
-<br/></br>
-<br/></br>
-
-<tab>file4_Types_of_critical_points
-
-![file4_Types_of_critical_points](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.gif?raw=true)
-<br/></br>
-<br/></br>
-
-<tab>file5_f(x,y)=(y-x)(1-2x-3y)
-
-![file5_f(x,y)=(y-x)(1-2x-3y)](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/approximations-and-optimizations/Critical-Points/file5_f(x%2Cy)%3D(y-x)(1-2x-3y).gif?raw=true)
-<br/></br>
-<br/></br>
diff --git a/FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py b/FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py
deleted file mode 100644
index 984db16..0000000
--- a/FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py
+++ /dev/null
@@ -1,34 +0,0 @@
-from manimlib.imports import*
-
-class TangenttoSurface(ThreeDScene):
-
- def construct(self):
- axes = ThreeDAxes()
-
- #----f(x,y): x**2+y**2
- p = 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_C,GREEN_D],
- resolution = (20, 20)).scale(1)
- self.set_camera_orientation(phi = 75*DEGREES)
-
- h_text = TextMobject("The graph tends to coincide with its tangent plane").scale(0.5).to_corner(UL)
- d = Dot([0,0,0],color ='#800000') #----critical point
- r = Rectangle(height = 2,breadth = 1,color = YELLOW).scale(0.5) #----tangent plane to critical point
- line1 = DashedLine(color=RED).shift(4*UP+1.3*RIGHT).rotate(1.571,UP).scale(1.2)
- line2 = DashedLine(color=RED).shift(4*UP-1.3*RIGHT).rotate(1.571,UP).scale(1.2)
-
- r2 = Rectangle(height = 2, breadth = 1,color = GREEN, fill_opacity=0.3).scale(0.5)
-
- self.add(axes)
- self.play(Write(r))
- self.play(Write(p),Write(d))
- self.play(ShowCreation(line1),ShowCreation(line2))
- self.wait(2)
-
- self.play(FadeOut(line1),FadeOut(line2),ReplacementTransform(p,r2))
- self.add_fixed_in_frame_mobjects(h_text)
- self.wait(1)
diff --git a/FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file3_non_differentiable_function.py b/FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file3_non_differentiable_function.py
deleted file mode 100644
index 13bd73e..0000000
--- a/FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file3_non_differentiable_function.py
+++ /dev/null
@@ -1,30 +0,0 @@
-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()
-
- #----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)
-
- self.set_camera_orientation(phi = 75 * DEGREES)
-
- d = Dot([0,0,0],color = '#800000') #----critical point
- d_text = TextMobject("$(0,0)$").scale(0.5).shift(0.2*DOWN)
- f_text = TextMobject("$f$ is not differentiable at origin").scale(0.5).to_corner(UL)
-
- self.begin_ambient_camera_rotation(rate=0.1)
- self.add(axes)
- self.play(Write(p),Write(d))
- self.add_fixed_in_frame_mobjects(d_text)
- self.add_fixed_in_frame_mobjects(f_text)
- self.wait(2)
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..5bd9cc5
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/README.md
@@ -0,0 +1,32 @@
+<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_Types_of_critical_points
+
+![file4_Types_of_critical_points](https://github.com/vnb09/FSF-mathematics-python-code-archive/blob/fsf_tasks/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.gif?raw=true)
+<br/></br>
+<br/></br>
+
+<tab>file5_f(x,y)=(y-x)(1-2x-3y)
+
+![file5_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/file5_f(x%2Cy)%3D(y-x)(1-2x-3y).gif?raw=true)
+<br/></br>
+<br/></br>
diff --git a/FSF-2020/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
index ca3989c..ca3989c 100644
--- a/FSF-2020/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
Binary files differ
diff --git a/FSF-2020/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
index e8cb08d..e8cb08d 100644
--- a/FSF-2020/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
diff --git a/FSF-2020/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
index 84acf2e..84acf2e 100644
--- a/FSF-2020/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
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diff --git a/FSF-2020/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
index 4b020e1..4b020e1 100644
--- a/FSF-2020/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
diff --git a/FSF-2020/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
index 14fb318..14fb318 100644
--- a/FSF-2020/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
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diff --git a/FSF-2020/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
index e674113..e674113 100644
--- a/FSF-2020/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
diff --git a/FSF-2020/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.gif
index 91e7084..91e7084 100644
--- a/FSF-2020/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.gif
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.gif
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diff --git a/FSF-2020/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.py
index 656fb68..656fb68 100644
--- a/FSF-2020/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.py
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file4_Types_of_critical_points.py
diff --git a/FSF-2020/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).gif
index 4bc92f8..4bc92f8 100644
--- a/FSF-2020/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).gif
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).gif
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diff --git a/FSF-2020/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).py
index 41c3b61..41c3b61 100644
--- a/FSF-2020/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).py
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Critical-Points/file5_f(x,y)=(y-x)(1-2x-3y).py
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..1e1782e
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.gif
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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..17f31ac
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file1_Extrema_over_g(x,y)=k.py
@@ -0,0 +1,53 @@
+from manimlib.imports import*
+
+class firstScene(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes()
+ 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('#F0FFFF').fade(0.4)
+
+ c = Circle().set_color('#FF00FF').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)
+
+ l1 = DashedLine([-0.5,0.5,0.9],[-0.5,0.5,0],color = '#F08080')
+ l2 = DashedLine([0.1,0,2.1],[0.1,0,0],color = '#F08080')
+
+ c2 = Circle(fill_opacity= 0.5).shift([-0.3,0.2,0]).scale(0.4)
+
+ minima_refl = Dot(color = '#4682B4').shift([-0.5,0.5,0]).rotate(1.571,UP)
+ maxima_refl = Dot(color = '#4682B4').shift([0.1,0,0]).rotate(1.571,UP)
+
+ max_text = TextMobject("maximum over $g(x,y)=k$",color = '#FFA074').shift([-1.7,0,0]).scale(0.5).shift(2.2*UP)
+ min_text = TextMobject("minimum over $g(x,y)=k$",color = '#FFA074').shift([2.5,0.5,1]).scale(0.5).shift(0.5*UP)
+ label_f = TextMobject("$z=f(x,y)$",color = '#8A2BE2').scale(0.5).shift(3*UP+3*RIGHT)
+ label_g = TextMobject("$g(x,y)=k$",color = '#8A2BE2').scale(0.5).shift(2*RIGHT)
+
+
+ self.add(axes)
+ 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.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)
+ self.play(ShowCreation(l1),ShowCreation(l2))
+ self.play(Write(c2))
+ self.add_fixed_in_frame_mobjects(label_g)
+ self.wait(1)
+ self.play(Write(maxima_refl))
+ self.play(Write(minima_refl))
+ 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..b22afb3
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.gif
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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..4374ff7
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file2_Geometric_Proof.py
@@ -0,0 +1,68 @@
+from manimlib.imports import*
+
+class firstScene(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes().scale(0.7).rotate(math.radians(180))
+ 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,checkerboard_colors=[GREEN_C, GREEN_E]).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_df = Arrow(color = '#00FFFF').rotate(1.1).shift(0.82*LEFT+0.15*UP) #---- f parallel to g
+ b_dg = 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)
+
+ level_Curve = VGroup(l1,l2,l3,l4,l5,l6,l7,l8,l9,l10,l11,l12,l13,l14,l15)
+
+ 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)
+
+
+
+ self.add(axes)
+ self.set_camera_orientation(phi=0 * DEGREES, theta = 90*DEGREES)
+ self.play(Write(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.play(ShowCreation(b_dg))
+ self.wait(1)
+ self.add_fixed_in_frame_mobjects(f_text)
+ 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_Optimizing_function_w.r.t_one_constraint.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Optimizing_function_w.r.t_one_constraint.gif
new file mode 100644
index 0000000..9602283
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Optimizing_function_w.r.t_one_constraint.gif
Binary files differ
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Optimizing_function_w.r.t_one_constraint.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Optimizing_function_w.r.t_one_constraint.py
new file mode 100644
index 0000000..bf75dd8
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Lagrange-Multipliers/file3_Optimizing_function_w.r.t_one_constraint.py
@@ -0,0 +1,29 @@
+from manimlib.imports import*
+
+class firstScene(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes()
+ cylinder = ParametricSurface(
+ lambda u, v: np.array([
+ np.cos(TAU * v),
+ np.sin(TAU * v),
+ 2 * (u)
+ ]),checkerboard_colors=[YELLOW_C,YELLOW_D,YELLOW_E]
+ ).fade(0.4) #Resolution of the surfaces
+
+ plane = ParametricSurface(
+ lambda u, v: np.array([
+ u,
+ v,
+ u+v
+ ]),checkerboard_colors=[TEAL_C,TEAL_D,TEAL_E]
+ ).scale(2.5)
+ self.add(axes)
+ self.set_camera_orientation(phi=75*DEGREES,theta=45*DEGREES)
+ self.play(Write(cylinder))
+ self.play(Write(plane))
+ self.wait(1)
+ self.begin_ambient_camera_rotation(rate=0.7)
+ self.wait(5)
+ self.move_camera(phi=35*DEGREES,theta=-45*DEGREES)
+ self.wait(2)
diff --git a/FSF-2020/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
index 2b8bf5f..2b8bf5f 100644
--- a/FSF-2020/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
Binary files differ
diff --git a/FSF-2020/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
index 4c17f90..4c17f90 100644
--- a/FSF-2020/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
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..d23405d
--- /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..d1ecf8c
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file2_Tangent_plane_approximation_visualization.py
@@ -0,0 +1,74 @@
+from manimlib.imports import*
+
+#---- tangent plane is parallel to the x-y plane
+class MaximaScene(ThreeDScene):
+ def construct(self):
+
+ axes = ThreeDAxes().scale(1.2)
+ label_x= TextMobject("$x$").shift([5.4,-0.5,0]) #---- x axis
+ label_y= TextMobject("$y$").shift([-0.5,5.2,0]).rotate(-4.5) #---- 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]).scale(1.5).shift([-0.8,0.5,1.5])
+
+ d1 = Dot([0.2,2.01,2.24],color = '#800000').rotate(1.1,LEFT) #---- point(x_0,y_0)
+ d1_copy = Dot([1.1,2.2,-0.45],color = '#800000') #---- projection of point(x_0,y_0) on x-y plane
+ d1_text = TextMobject("$(x_0,y_0)$",color = "#8B0000").scale(0.4).shift(1.3*RIGHT+1.1*UP)
+
+ d2 = Dot([1.1,2.2,2.7],color = '#800000').rotate(1,LEFT) #---- point(x,y)
+ d2_copy = Dot([0.1,1.95,0.4],color = '#800000') #---- projection of point(x,y) on x-y plane
+ d2_text = TextMobject("$(x,y)$",color = "#8B0000").scale(0.4).shift(0.6*RIGHT+0.8*UP)
+
+ t_plane = Rectangle(color = PURPLE, fill_opacity=0.3).scale(0.4).rotate(1,LEFT).shift([1.1,2.5,2.9]) #---- tangent plane
+
+ t_text= TextMobject("Tangent Plane",color = RED).scale(0.5).shift(0.3*RIGHT+1.3*UP).rotate(math.radians(5),LEFT)
+
+ l1 = Line([1.1,2.2,2.6],[1.1,2.2,-0.45]).fade(0.2)
+ l2 = Line([0.1,1.95,2.05],[0.1,1.95,0.4]).fade(0.2)
+
+ a1 = Line([0.1,1.95,0.4],[1.1,2.2,-0.45],color ="#00FF7F")
+ a_x = Line([0.1,1.95,0.4],[1.7,1.95,0.4],color ="#9400D3")
+ a_y = Line([0.1,1.95,0.4],[0.1,2.75,0.4],color ="#8B4513")
+ a2 = Line([1.7,1.95,0.4],[1.7,2.75,0.4])
+ a3 = Line([0.1,2.75,0.4],[1.7,2.75,0.4])
+
+ #---- transition of tangent plane
+
+ t2_plane = Rectangle(color = PURPLE, fill_opacity=0.3).scale(0.4).rotate(1,LEFT).shift([1.1,2.5,2])
+ t3_plane = Rectangle(color = PURPLE, fill_opacity=0.3).scale(0.4).rotate(math.radians(180),LEFT).shift([1.1,2.5,2])
+ t4_plane = Rectangle(color = PURPLE, fill_opacity=0.3).scale(0.4).rotate(math.radians(180),LEFT).shift([0.9,2.35,0.4])
+
+ #-------------------------------------------
+ self.set_camera_orientation(phi = 50 * DEGREES, theta = 45 * 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(d1))
+ self.add_fixed_in_frame_mobjects(d1_text)
+ self.play(ShowCreation(t_plane))
+ self.add_fixed_in_frame_mobjects(t_text)
+ self.wait(1)
+ self.play(FadeOut(t_text),Write(d2))
+ self.add_fixed_in_frame_mobjects(d2_text)
+ self.wait(1)
+ self.play(Write(l1),Write(l2))
+ self.play(Write(d2_copy),Write(d1_copy))
+ self.wait(1)
+ self.play(Write(a1),Write(a_x),Write(a_y))
+ self.wait(1)
+ self.play(Write(a2),Write(a3))
+ self.wait(1)
+ self.play(ReplacementTransform(t_plane,t2_plane))
+ self.wait(1)
+ self.play(ReplacementTransform(t2_plane,t3_plane))
+ self.wait(1)
+ self.play(ReplacementTransform(t3_plane,t4_plane))
+ 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..cfe054b
--- /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/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent plane_at_critical_points.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.py
index d129213..d129213 100644
--- a/FSF-2020/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent plane_at_critical_points.py
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Tangent-Plane-Approximations/file4_Tangent_plane_at_extrema_and_saddle_point.py
diff --git a/FSF-2020/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
index 3471e4d..3471e4d 100644
--- a/FSF-2020/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
Binary files differ
diff --git a/FSF-2020/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
index 84052cc..84052cc 100644
--- a/FSF-2020/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
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.gif
new file mode 100644
index 0000000..d49cdd5
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.gif
Binary files differ
diff --git a/FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.py
index c1e3516..c1e3516 100644
--- a/FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.py
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file2_Degenerate_Hessian_Matrix.py
diff --git a/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.gif b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.gif
new file mode 100644
index 0000000..2b0acb3
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.gif
Binary files differ
diff --git a/FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.py b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.py
index 3056842..3056842 100644
--- a/FSF-2020/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.py
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/The-Second-Derivative-Test/file3_Nondegenerate_Hessian_Matrix.py
diff --git a/FSF-2020/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
index 129fedc..129fedc 100644
--- a/FSF-2020/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
Binary files differ
diff --git a/FSF-2020/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
index d3084e2..d3084e2 100644
--- a/FSF-2020/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
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..e00a946
--- /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..a097a96
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file1_Visualization_of_dz.py
@@ -0,0 +1,53 @@
+from manimlib.imports import*
+
+
+class firstScene(ThreeDScene):
+
+ def construct(self):
+
+ axes = ThreeDAxes().rotate(1.571)
+ 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)
+ d2 = Dot([2,2,1],color = '#00FFFF').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+0.9*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.add(axes)
+ self.set_camera_orientation(phi=75*DEGREES,theta=-10*DEGREES)
+ 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..620b49e
--- /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..b40be70
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file2_Differentials.py
@@ -0,0 +1,72 @@
+from manimlib.imports import*
+
+
+class firstScene(ThreeDScene):
+
+ def construct(self):
+
+ axes = ThreeDAxes()
+
+ s = Rectangle(color = '#00FF7F',fill_opacity=0.3).shift(2.3*UP+3.9*LEFT).scale(1).rotate(0.2,UP) #----surface z = f(x,y)
+
+ label_y = TextMobject("$y$").shift(5*RIGHT+0.4*DOWN).rotate(1.571)
+ label_x = TextMobject("$x$").shift(-0.1*UP+5.6*RIGHT).scale(0.5)
+
+ 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(0.7)
+ l4 = Line(color = '#FFDAB9').scale(0.6).shift(2.86*UP+0.9*RIGHT).rotate(1.571,DOWN).fade(0.7)
+
+ 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.add(axes)
+ self.set_camera_orientation(phi=75*DEGREES,theta=10*DEGREES)
+ self.play(Write(plane))
+ self.play(ShowCreation(label_y))
+ self.add_fixed_in_frame_mobjects(label_x)
+ self.play(Write(s))
+ 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..5aae2a1
--- /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..b29a7a3
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file3_Total_differential_of_z.py
@@ -0,0 +1,91 @@
+from manimlib.imports import*
+
+class firstScene(ThreeDScene):
+ def construct(self):
+ axes = ThreeDAxes().fade(0.5)
+ 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(s2))
+ self.wait(1)
+ self.play(Write(l1),Write(l2),Write(l3))
+ self.wait(1)
+ self.play(Write(s1))
+ self.wait(1)
+ 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(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..4f4627d
--- /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..83017ed
--- /dev/null
+++ b/FSF-2020/calculus-of-several-variables/approximations-and-optimizations/Total-Differential/file5_Total_differential_approximation.py
@@ -0,0 +1,48 @@
+from manimlib.imports import*
+
+
+class firstScene(ThreeDScene):
+
+ def construct(self):
+
+ axes = ThreeDAxes().rotate(1.571)
+ 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.add(axes)
+ self.set_camera_orientation(phi=75*DEGREES,theta=-10*DEGREES)
+ 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)