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from manimlib.imports import *
def pendulum_vector_field_func(point):
#theta, omega = point[:2]
return np.array([
5*point[0]+point[1],
3*point[1]+3*point[1],
0,
])
class SF(Scene):
CONFIG = {
#"func": cylinder_flow_vector_field,
"flow_time": 5,
}
def initialize_vector_field(self):
self.vector_field = VectorField(
pendulum_vector_field_func,
)
self.vector_field.sort(get_norm)
def construct(self):
# plane = NumberPlane(color=RED)
# plane.add(plane.get_axis_labels())
# self.add(plane)
A=TextMobject("The net flux through the green circular region is zero",tex_to_color_map={"green": GREEN})
B=TextMobject("The net flux through the blue circular region is non-zero",tex_to_color_map={"blue": BLUE})
c1=Circle(color=GREEN, radius=1.5)
c1.shift(4*LEFT+2.2*UP)
c2=Circle(color=BLUE, radius=1.5)
self.play(ShowCreation(A))
self.wait(0.5)
self.play(ApplyMethod(A.shift, (0.8*UP+0.2*LEFT)))
self.play(ShowCreation(B))
# self.play(ApplyMethod(B.shift, (2*UP)))
self.wait(2)
self.play(FadeOut(A),FadeOut(B))
self.initialize_vector_field()
field = self.vector_field
self.play(ShowCreation(field), run_time=4)
self.play(ShowCreation(c1))
self.play(ShowCreation(c2))
self.wait(1)
lines = StreamLines(
pendulum_vector_field_func,
virtual_time=3,
min_magnitude=0,
max_magnitude=2,
)
self.add(AnimatedStreamLines(
lines,
line_anim_class=ShowPassingFlash
))
self.wait(2)
phase_point = VectorizedPoint(1*UP+1*RIGHT)
self.add(move_along_vector_field(phase_point, pendulum_vector_field_func))
self.wait(2)
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