def setup(self):
self.input_color = YELLOW_C
self.output_color = RED
def spiril(t):
theta = 2*np.pi*t
return t*np.cos(theta)*RIGHT+t*np.sin(theta)*UP
self.spiril1 = ParametricFunction(
lambda t : 1.5*RIGHT + DOWN + 2*spiril(t),
density = 5*DEFAULT_POINT_DENSITY_1D,
)
self.spiril2 = ParametricFunction(
lambda t : 5.5*RIGHT + UP - 2*spiril(1-t),
density = 5*DEFAULT_POINT_DENSITY_1D,
)
Mobject.align_data(self.spiril1, self.spiril2)
self.output = Mobject(self.spiril1, self.spiril2)
self.output.ingest_submobjects()
self.output.highlight(GREEN_A)
self.interval = UnitInterval()
self.interval.scale_to_fit_width(SPACE_WIDTH-1)
self.interval.to_edge(LEFT)
self.input_dot = Dot(color = self.input_color)
self.output_dot = self.input_dot.copy().highlight(self.output_color)
left, right = self.interval.get_left(), self.interval.get_right()
self.input_homotopy = lambda (x, y, z, t) : (x, y, t) + interpolate(left, right, t)
output_size = self.output.get_num_points()-1
output_points = self.output.points
self.output_homotopy = lambda (x, y, z, t) : (x, y, z) + output_points[int(t*output_size)]
def construct(self, order):
if order == 2:
result_tex = "(0.125, 0.75)"
elif order == 3:
result_tex = "(0.0758, 0.6875)"
phc, arg, result = TexMobject([
"\\text{PHC}_%d"%order,
"(0.3)",
"= %s"%result_tex
]).to_edge(UP).split()
function = TextMobject("Function", size = "\\normal")
function.shift(phc.get_center()+DOWN+2*LEFT)
function_arrow = Arrow(function, phc)
line = Line(5*LEFT, 5*RIGHT)
curve = HilbertCurve(order = order)
line.match_colors(curve)
grid = Grid(2**order, 2**order)
grid.fade()
for mob in curve, grid:
mob.scale(0.7)
index = int(0.3*line.get_num_points())
dot1 = Dot(line.points[index])
arrow1 = Arrow(arg, dot1, buff = 0.1)
dot2 = Dot(curve.points[index])
arrow2 = Arrow(result.get_bottom(), dot2, buff = 0.1)
self.add(phc)
self.play(
ShimmerIn(function),
ShowCreation(function_arrow)
)
self.wait()
self.remove(function_arrow, function)
self.play(ShowCreation(line))
self.wait()
self.play(
ShimmerIn(arg),
ShowCreation(arrow1),
ShowCreation(dot1)
)
self.wait()
self.remove(arrow1)
self.play(
FadeIn(grid),
Transform(line, curve),
Transform(dot1, dot2),
run_time = 2
)
self.wait()
self.play(
ShimmerIn(result),
ShowCreation(arrow2)
)
self.wait()
def construct(self):
val = 0.3
text = TextMobject([
"PHC", "$_n", "(", "%3.1f"%val, ")$",
" has a ", "limit point ", "as $n \\to \\infty$"
])
func_parts = text.copy().split()[:5]
Mobject(*func_parts).center().to_edge(UP)
num_str, val_str = func_parts[1], func_parts[3]
curve = UnitInterval()
curve.sort_points(lambda p : p[0])
dot = Dot().shift(curve.number_to_point(val))
arrow = Arrow(val_str, dot, buff = 0.1)
curve.add_numbers(0, 1)
self.play(ShowCreation(curve))
self.play(
ShimmerIn(val_str),
ShowCreation(arrow),
ShowCreation(dot)
)
self.wait()
self.play(
FadeOut(arrow),
*[
FadeIn(func_parts[i])
for i in 0, 1, 2, 4
]
)
for num in range(2,9):
new_curve = HilbertCurve(order = num)
new_curve.scale(0.8)
new_dot = Dot(new_curve.points[int(val*new_curve.get_num_points())])
new_num_str = TexMobject(str(num)).replace(num_str)
self.play(
Transform(curve, new_curve),
Transform(dot, new_dot),
Transform(num_str, new_num_str)
)
self.wait()
text.to_edge(UP)
text_parts = text.split()
for index in 1, -1:
text_parts[index].highlight()
starters = Mobject(*func_parts + [
Point(mob.get_center(), stroke_width=1)
for mob in text_parts[5:]
])
self.play(Transform(starters, text))
arrow = Arrow(text_parts[-2].get_bottom(), dot, buff = 0.1)
self.play(ShowCreation(arrow))
self.wait()
def __init__(self, mobject_or_point, **kwargs):
digest_config(self, kwargs)
big_dot = Dot(
radius = SPACE_WIDTH+SPACE_HEIGHT,
stroke_width = 0,
fill_color = self.color,
fill_opacity = 0,
)
little_dot = Dot(radius = 0)
little_dot.set_fill(self.color, opacity = self.opacity)
little_dot.move_to(mobject_or_point)
Transform.__init__(self, big_dot, little_dot, **kwargs)
def construct(self):
big_grid_dim = 20.
small_grid_dim = 6.
big_grid = Grid(64, 64, height=big_grid_dim, width=big_grid_dim)
big_grid.to_corner(UP + RIGHT, buff=2)
small_grid = big_grid.copy()
small_grid.scale(small_grid_dim / big_grid_dim)
small_grid.center()
pixel = MobjectFromRegion(
region_from_polygon_vertices(
*0.2 *
np.array([RIGHT + DOWN, RIGHT + UP, LEFT + UP, LEFT + DOWN])))
pixel.set_color(WHITE)
pixel_width = big_grid.width / big_grid.columns
pixel.scale_to_fit_width(pixel_width)
pixel.to_corner(UP + RIGHT, buff=2)
pixel.shift(5 * pixel_width * (2 * LEFT + DOWN))
freq_line = get_freq_line()
dot = Dot()
dot.shift(freq_line.get_center() + 2 * RIGHT)
string = Line(LEFT, RIGHT, color=GREEN)
arrow = Arrow(dot, string.get_center())
vibration_config = {
"overtones": 1,
"spatial_period": 2,
}
vibration, loud_vibration, quiet_vibration = [
Vibrate(string.copy(), amplitude=a, **vibration_config)
for a in [0.5, 1., 0.25]
]
self.add(small_grid)
self.dither()
self.play(Transform(small_grid, big_grid))
self.play(FadeIn(pixel))
self.dither()
self.play(FadeOut(small_grid), ShowCreation(freq_line))
self.remove(small_grid)
self.play(Transform(pixel, dot), )
self.dither()
self.play(ShowCreation(arrow))
self.play(loud_vibration)
self.play(TransformAnimations(loud_vibration, quiet_vibration),
ApplyMethod(dot.fade, 0.9))
self.clear()
self.add(freq_line, dot, arrow)
self.play(quiet_vibration)
def setup(self):
self.input_color = YELLOW_C
self.output_color = RED
def spiril(t):
theta = 2*np.pi*t
return t*np.cos(theta)*RIGHT+t*np.sin(theta)*UP
self.spiril1 = ParametricFunction(
lambda t : 1.5*RIGHT + DOWN + 2*spiril(t),
density = 5*DEFAULT_POINT_DENSITY_1D,
)
self.spiril2 = ParametricFunction(
lambda t : 5.5*RIGHT + UP - 2*spiril(1-t),
density = 5*DEFAULT_POINT_DENSITY_1D,
)
Mobject.align_data(self.spiril1, self.spiril2)
self.output = Mobject(self.spiril1, self.spiril2)
self.output.ingest_sub_mobjects()
self.output.highlight(GREEN_A)
self.interval = UnitInterval()
self.interval.scale_to_fit_width(SPACE_WIDTH-1)
self.interval.to_edge(LEFT)
self.input_dot = Dot(color = self.input_color)
self.output_dot = self.input_dot.copy().highlight(self.output_color)
left, right = self.interval.get_left(), self.interval.get_right()
self.input_homotopy = lambda (x, y, z, t) : (x, y, t) + interpolate(left, right, t)
output_size = self.output.get_num_points()-1
output_points = self.output.points
self.output_homotopy = lambda (x, y, z, t) : (x, y, z) + output_points[int(t*output_size)]
def construct(self):
start_curve = SnakeCurve(order = 6)
end_curve = SnakeCurve(order = 7)
start_dots, end_dots = [
Mobject(*[
Dot(
curve.points[int(x*curve.get_num_points())],
color = color
)
for x, color in [
(0.202, GREEN),
(0.48, BLUE),
(0.7, RED)
]
])
for curve in start_curve, end_curve
]
self.add(start_curve)
self.dither()
self.play(
ShowCreation(start_dots, run_time = 2),
ApplyMethod(start_curve.fade)
)
end_curve.fade()
self.play(
Transform(start_curve, end_curve),
Transform(start_dots, end_dots)
)
self.dither()
def construct(self):
line = get_freq_line().center()
line.sort_points(lambda p: p[0])
curves = [self.CURVE_CLASS(order=order) for order in range(3, 10)]
alpha = 0.48
dot = Dot(UP)
start_dot = Dot(0.1 * LEFT)
dots = [
Dot(curve.points[alpha * curve.get_num_points()])
for curve in curves
]
self.play(ShowCreation(line))
self.play(Transform(dot, start_dot))
self.dither()
for new_dot, curve in zip(dots, curves):
self.play(Transform(line, curve), Transform(dot, new_dot))
self.dither()
def construct(self):
val = 0.7
text = TexMobject([
"\\text{HC}(", "x", ")",
"=\\lim_{n \\to \\infty}\\text{PHC}_n(", "x", ")"
])
text.to_edge(UP)
x1 = text.split()[1]
x2 = text.split()[-2]
x2.highlight(BLUE)
explanation = TextMobject("Actual Hilbert curve function")
exp_arrow = Arrow(explanation, text.split()[0])
curve = UnitInterval()
dot = Dot(curve.number_to_point(val))
x_arrow = Arrow(x1.get_bottom(), dot, buff = 0)
curve.sort_points(lambda p : p[0])
curve.add_numbers(0, 1)
self.add(*text.split()[:3])
self.play(
ShimmerIn(explanation),
ShowCreation(exp_arrow)
)
self.wait()
self.remove(explanation, exp_arrow)
self.play(ShowCreation(curve))
self.play(
ApplyMethod(x1.highlight, BLUE),
ShowCreation(x_arrow),
ShowCreation(dot)
)
self.wait()
self.remove(x_arrow)
limit = Mobject(*text.split()[3:]).ingest_submobjects()
limit.stroke_width = 1
self.play(ShimmerIn(limit))
for num in range(1, 9):
new_curve = HilbertCurve(order = num)
new_curve.scale(0.8)
new_dot = Dot(new_curve.points[int(val*new_curve.get_num_points())])
self.play(
Transform(curve, new_curve),
Transform(dot, new_dot),
)
def increment(self, run_time_per_anim = 1):
moving_dot = Dot(
self.counting_dot_starting_position,
radius = self.count_dot_starting_radius,
color = self.digit_place_colors[0],
)
moving_dot.generate_target()
moving_dot.set_fill(opacity = 0)
kwargs = {
"run_time" : run_time_per_anim
}
continue_rolling_over = True
first_move = True
place = 0
while continue_rolling_over:
added_anims = []
if first_move:
added_anims += self.get_digit_increment_animations()
first_move = False
moving_dot.target.replace(
self.dot_template_iterators[place].next()
)
self.play(MoveToTarget(moving_dot), *added_anims, **kwargs)
self.curr_configurations[place].add(moving_dot)
if len(self.curr_configurations[place].split()) == self.get_place_max(place):
full_configuration = self.curr_configurations[place]
self.curr_configurations[place] = VGroup()
place += 1
center = full_configuration.get_center_of_mass()
radius = 0.6*max(
full_configuration.get_width(),
full_configuration.get_height(),
)
circle = Circle(
radius = radius,
stroke_width = 0,
fill_color = self.digit_place_colors[place],
fill_opacity = 0.5,
)
circle.move_to(center)
moving_dot = VGroup(circle, full_configuration)
moving_dot.generate_target()
moving_dot[0].set_fill(opacity = 0)
else:
continue_rolling_over = False
def construct(self):
text = TextMobject([
"PHC", "_n", "(", "x", ")$",
" has a limit point ", "as $n \\to \\infty$",
"\\\\ for all $x$"
])
parts = text.split()
parts[-1].next_to(Mobject(*parts[:-1]), DOWN)
parts[-1].highlight(BLUE)
parts[3].highlight(BLUE)
parts[1].highlight()
parts[-2].highlight()
text.to_edge(UP)
curve = UnitInterval()
curve.sort_points(lambda p : p[0])
vals = np.arange(0.1, 1, 0.1)
dots = Mobject(*[
Dot(curve.number_to_point(val))
for val in vals
])
curve.add_numbers(0, 1)
starter_dots = dots.copy().ingest_submobjects()
starter_dots.shift(2*UP)
self.add(curve, text)
self.wait()
self.play(DelayByOrder(ApplyMethod(starter_dots.shift, 2*DOWN)))
self.wait()
self.remove(starter_dots)
self.add(dots)
for num in range(1, 10):
new_curve = HilbertCurve(order = num)
new_curve.scale(0.8)
new_dots = Mobject(*[
Dot(new_curve.points[int(val*new_curve.get_num_points())])
for val in vals
])
self.play(
Transform(curve, new_curve),
Transform(dots, new_dots),
)
def construct(self):
grid = get_grid()
grid.scale_to_fit_width(6)
grid.to_edge(LEFT)
freq_line = get_freq_line()
freq_line.scale_to_fit_width(6)
freq_line.center().to_edge(RIGHT)
arrow = Arrow(grid, freq_line)
color1, color2 = YELLOW_C, RED
square_length = 0.01
dot1 = Dot(color = color1)
dot1.shift(3*RIGHT)
dot2 = Dot(color = color2)
dot2.shift(3.1*RIGHT)
arrow1 = Arrow(2*RIGHT+UP, dot1, color = color1, buff = 0.1)
arrow2 = Arrow(4*RIGHT+UP, dot2, color = color2, buff = 0.1)
dot3, arrow3 = [
mob.copy().shift(5*LEFT+UP)
for mob in dot1, arrow1
]
dot4, arrow4 = [
mob.copy().shift(5*LEFT+0.9*UP)
for mob in dot2, arrow2
]
self.add(grid, freq_line, arrow)
self.dither()
self.play(ApplyMethod(
arrow.rotate, np.pi,
path_func = clockwise_path()
))
self.dither()
self.play(ShowCreation(arrow1))
self.add(dot1)
self.play(ShowCreation(arrow2))
self.add(dot2)
self.dither()
self.remove(arrow1, arrow2)
self.play(
Transform(dot1, dot3),
Transform(dot2, dot4)
)
self.play(
ApplyMethod(grid.fade, 0.8),
Animation(Mobject(dot3, dot4))
)
self.play(ShowCreation(arrow3))
self.play(ShowCreation(arrow4))
self.dither()
def get_dot_template(self, place):
#This should be replaced for non-base-10 counting scenes
down_right = (0.5) * RIGHT + (np.sqrt(3) / 2) * DOWN
dots = VGroup(*[
Dot(
point,
radius=0.25,
fill_opacity=0,
stroke_width=2,
stroke_color=WHITE,
) for point in self.get_template_configuration(place)
])
dots.scale_to_fit_height(self.dot_configuration_height)
return dots
def __init__(self, mobject_or_point, **kwargs):
digest_config(self, kwargs)
big_dot = Dot(
radius=SPACE_WIDTH + SPACE_HEIGHT,
stroke_width=0,
fill_color=self.color,
fill_opacity=0,
)
little_dot = Dot(radius=0)
little_dot.set_fill(self.color, opacity=self.opacity)
little_dot.move_to(mobject_or_point)
Transform.__init__(self, big_dot, little_dot, **kwargs)
def __init__(self, mobject_or_point, **kwargs):
digest_config(self, kwargs)
big_dot = Dot(
radius = FRAME_X_RADIUS+FRAME_Y_RADIUS,
stroke_width = 0,
fill_color = self.color,
fill_opacity = 0,
)
little_dot = Dot(radius = 0)
little_dot.set_fill(self.color, opacity = self.opacity)
little_dot.move_to(mobject_or_point)
Transform.__init__(self, big_dot, little_dot, **kwargs)
def construct(self):
start_words = TextMobject([
"``", "Space Filling", "Curve ''",
]).to_edge(TOP, buff = 0.25)
quote, space_filling, curve_quote = start_words.copy().split()
curve_quote.shift(
space_filling.get_left()-\
curve_quote.get_left()
)
space_filling = Point(space_filling.get_center())
end_words = Mobject(*[
quote, space_filling, curve_quote
]).center().to_edge(TOP, buff = 0.25)
space_filling_fractal = TextMobject("""
``Space Filling Fractal''
""").to_edge(UP)
curve = HilbertCurve(order = 2).shift(DOWN)
fine_curve = HilbertCurve(order = 8)
fine_curve.replace(curve)
dots = Mobject(*[
Dot(
curve.points[n*curve.get_num_points()/15],
color = YELLOW_C
)
for n in range(1, 15)
if n not in [4, 11]
])
start_words.shift(2*(UP+LEFT))
self.play(
ApplyMethod(start_words.shift, 2*(DOWN+RIGHT))
)
self.wait()
self.play(Transform(start_words, end_words))
self.wait()
self.play(ShowCreation(curve))
self.wait()
self.play(ShowCreation(
dots,
run_time = 3,
))
self.wait()
self.clear()
self.play(ShowCreation(fine_curve, run_time = 5))
self.wait()
self.play(ShimmerIn(space_filling_fractal))
self.wait()
def show_ghost_movement(self, vector):
if isinstance(vector, Arrow):
vector = vector.get_end() - vector.get_start()
elif len(vector) == 2:
vector = np.append(np.array(vector), 0.0)
x_max = int(SPACE_WIDTH + abs(vector[0]))
y_max = int(SPACE_HEIGHT + abs(vector[1]))
dots = VMobject(*[
Dot(x * RIGHT + y * UP) for x in range(-x_max, x_max)
for y in range(-y_max, y_max)
])
dots.set_fill(BLACK, opacity=0)
dots_halfway = dots.copy().shift(vector / 2).set_fill(WHITE, 1)
dots_end = dots.copy().shift(vector)
self.play(Transform(dots, dots_halfway, rate_func=rush_into))
self.play(Transform(dots, dots_end, rate_func=rush_from))
self.remove(dots)
def construct(self):
overtones = 5
floor = 2 * DOWN
main_string = Vibrate(color=BLUE_D)
component_strings = [
Vibrate(num_periods=k + 1,
overtones=1,
color=color,
center=2 * DOWN + UP * k)
for k, color in zip(range(overtones),
Color(BLUE_E).range_to(WHITE, overtones))
]
dots = [
Dot(string.mobject.get_center(), color=string.mobject.get_color())
for string in component_strings
]
freq_line = get_freq_line()
freq_line.shift(floor)
freq_line.sort_points(np.linalg.norm)
brace = Brace(freq_line, UP)
words = TextMobject("Range of frequency values")
words.next_to(brace, UP)
self.play(*[
TransformAnimations(main_string.copy(), string, run_time=5)
for string in component_strings
])
self.clear()
self.play(*[
TransformAnimations(string, Animation(dot))
for string, dot in zip(component_strings, dots)
])
self.clear()
self.play(
ShowCreation(freq_line), GrowFromCenter(brace), ShimmerIn(words),
*[
Transform(dot,
dot.copy().scale(2).rotate(-np.pi / 2).shift(floor),
path_func=path_along_arc(np.pi / 3)) for dot in dots
])
self.dither(0.5)
class FormalDefinitionOfContinuity(Scene):
def construct(self):
self.setup()
self.label_spaces()
self.move_dot()
self.label_jump()
self.draw_circles()
self.vary_circle_sizes()
self.discontinuous_point()
def setup(self):
self.input_color = YELLOW_C
self.output_color = RED
def spiril(t):
theta = 2*np.pi*t
return t*np.cos(theta)*RIGHT+t*np.sin(theta)*UP
self.spiril1 = ParametricFunction(
lambda t : 1.5*RIGHT + DOWN + 2*spiril(t),
density = 5*DEFAULT_POINT_DENSITY_1D,
)
self.spiril2 = ParametricFunction(
lambda t : 5.5*RIGHT + UP - 2*spiril(1-t),
density = 5*DEFAULT_POINT_DENSITY_1D,
)
Mobject.align_data(self.spiril1, self.spiril2)
self.output = Mobject(self.spiril1, self.spiril2)
self.output.ingest_submobjects()
self.output.highlight(GREEN_A)
self.interval = UnitInterval()
self.interval.scale_to_fit_width(SPACE_WIDTH-1)
self.interval.to_edge(LEFT)
self.input_dot = Dot(color = self.input_color)
self.output_dot = self.input_dot.copy().highlight(self.output_color)
left, right = self.interval.get_left(), self.interval.get_right()
self.input_homotopy = lambda (x, y, z, t) : (x, y, t) + interpolate(left, right, t)
output_size = self.output.get_num_points()-1
output_points = self.output.points
self.output_homotopy = lambda (x, y, z, t) : (x, y, z) + output_points[int(t*output_size)]
def get_circles_and_points(self, min_input, max_input):
input_left, input_right = [
self.interval.number_to_point(num)
for num in min_input, max_input
]
input_circle = Circle(
radius = np.linalg.norm(input_left-input_right)/2,
color = WHITE
)
input_circle.shift((input_left+input_right)/2)
input_points = Line(
input_left, input_right,
color = self.input_color
)
output_points = Mobject(color = self.output_color)
n = self.output.get_num_points()
output_points.add_points(
self.output.points[int(min_input*n):int(max_input*n)]
)
output_center = output_points.points[int(0.5*output_points.get_num_points())]
max_distance = np.linalg.norm(output_center-output_points.points[-1])
output_circle = Circle(
radius = max_distance,
color = WHITE
)
output_circle.shift(output_center)
return (
input_circle,
input_points,
output_circle,
output_points
)
def label_spaces(self):
input_space = TextMobject("Input Space")
input_space.to_edge(UP)
input_space.shift(LEFT*SPACE_WIDTH/2)
output_space = TextMobject("Output Space")
output_space.to_edge(UP)
output_space.shift(RIGHT*SPACE_WIDTH/2)
line = Line(
UP*SPACE_HEIGHT, DOWN*SPACE_HEIGHT,
color = WHITE
)
self.play(
ShimmerIn(input_space),
ShimmerIn(output_space),
ShowCreation(line),
ShowCreation(self.interval),
)
self.wait()
def move_dot(self):
kwargs = {
"rate_func" : None,
"run_time" : 3
}
self.play(
Homotopy(self.input_homotopy, self.input_dot, **kwargs),
Homotopy(self.output_homotopy, self.output_dot, **kwargs),
ShowCreation(self.output, **kwargs)
)
self.wait()
def label_jump(self):
jump_points = Mobject(
Point(self.spiril1.points[-1]),
Point(self.spiril2.points[0])
)
self.brace = Brace(jump_points, RIGHT)
self.jump = TextMobject("Jump")
self.jump.next_to(self.brace, RIGHT)
self.play(
GrowFromCenter(self.brace),
ShimmerIn(self.jump)
)
self.wait()
self.remove(self.brace, self.jump)
def draw_circles(self):
input_value = 0.45
input_radius = 0.04
for dot in self.input_dot, self.output_dot:
dot.center()
kwargs = {
"rate_func" : lambda t : interpolate(1, input_value, smooth(t))
}
self.play(
Homotopy(self.input_homotopy, self.input_dot, **kwargs),
Homotopy(self.output_homotopy, self.output_dot, **kwargs)
)
A, B = map(Mobject.get_center, [self.input_dot, self.output_dot])
A_text = TextMobject("A")
A_text.shift(A+2*(LEFT+UP))
A_arrow = Arrow(
A_text, self.input_dot,
color = self.input_color
)
B_text = TextMobject("B")
B_text.shift(B+2*RIGHT+DOWN)
B_arrow = Arrow(
B_text, self.output_dot,
color = self.output_color
)
tup = self.get_circles_and_points(
input_value-input_radius,
input_value+input_radius
)
input_circle, input_points, output_circle, output_points = tup
for text, arrow in [(A_text, A_arrow), (B_text, B_arrow)]:
self.play(
ShimmerIn(text),
ShowCreation(arrow)
)
self.wait()
self.remove(A_text, A_arrow, B_text, B_arrow)
self.play(ShowCreation(input_circle))
self.wait()
self.play(ShowCreation(input_points))
self.wait()
input_points_copy = input_points.copy()
self.play(
Transform(input_points_copy, output_points),
run_time = 2
)
self.wait()
self.play(ShowCreation(output_circle))
self.wait()
self.wait()
self.remove(*[
input_circle, input_points,
output_circle, input_points_copy
])
def vary_circle_sizes(self):
input_value = 0.45
radius = 0.04
vary_circles = VaryCircles(
self, input_value, radius,
run_time = 5,
)
self.play(vary_circles)
self.wait()
text = TextMobject("Function is ``Continuous at A''")
text.shift(2*UP).to_edge(LEFT)
arrow = Arrow(text, self.input_dot)
self.play(
ShimmerIn(text),
ShowCreation(arrow)
)
self.wait()
self.remove(vary_circles.mobject, text, arrow)
def discontinuous_point(self):
point_description = TextMobject(
"Point where the function jumps"
)
point_description.shift(3*RIGHT)
discontinuous_at_A = TextMobject(
"``Discontinuous at A''",
size = "\\Large"
)
discontinuous_at_A.shift(2*UP).to_edge(LEFT)
text = TextMobject("""
Circle around ouput \\\\
points can never \\\\
be smaller than \\\\
the jump
""")
text.scale(0.75)
text.shift(3.5*RIGHT)
input_value = 0.5
input_radius = 0.04
vary_circles = VaryCircles(
self, input_value, input_radius,
run_time = 5,
)
for dot in self.input_dot, self.output_dot:
dot.center()
kwargs = {
"rate_func" : lambda t : interpolate(0.45, input_value, smooth(t))
}
self.play(
Homotopy(self.input_homotopy, self.input_dot, **kwargs),
Homotopy(self.output_homotopy, self.output_dot, **kwargs)
)
discontinuous_arrow = Arrow(discontinuous_at_A, self.input_dot)
arrow = Arrow(
point_description, self.output_dot,
buff = 0.05,
color = self.output_color
)
self.play(
ShimmerIn(point_description),
ShowCreation(arrow)
)
self.wait()
self.remove(point_description, arrow)
tup = self.get_circles_and_points(
input_value-input_radius,
input_value+input_radius
)
input_circle, input_points, output_circle, output_points = tup
input_points_copy = input_points.copy()
self.play(ShowCreation(input_circle))
self.play(ShowCreation(input_points))
self.play(
Transform(input_points_copy, output_points),
run_time = 2
)
self.play(ShowCreation(output_circle))
self.wait()
self.play(ShimmerIn(text))
self.remove(input_circle, input_points, output_circle, input_points_copy)
self.play(vary_circles)
self.wait()
self.play(
ShimmerIn(discontinuous_at_A),
ShowCreation(discontinuous_arrow)
)
self.wait(3)
self.remove(vary_circles.mobject, discontinuous_at_A, discontinuous_arrow)
def continuous_point(self):
pass
def construct(self):
big_grid_dim = 20.
small_grid_dim = 6.
big_grid = Grid(64, 64, height = big_grid_dim, width = big_grid_dim)
big_grid.to_corner(UP+RIGHT, buff = 2)
small_grid = big_grid.copy()
small_grid.scale(small_grid_dim/big_grid_dim)
small_grid.center()
pixel = MobjectFromRegion(
region_from_polygon_vertices(*0.2*np.array([
RIGHT+DOWN,
RIGHT+UP,
LEFT+UP,
LEFT+DOWN
]))
)
pixel.set_color(WHITE)
pixel_width = big_grid.width/big_grid.columns
pixel.scale_to_fit_width(pixel_width)
pixel.to_corner(UP+RIGHT, buff = 2)
pixel.shift(5*pixel_width*(2*LEFT+DOWN))
freq_line = get_freq_line()
dot = Dot()
dot.shift(freq_line.get_center() + 2*RIGHT)
string = Line(LEFT, RIGHT, color = GREEN)
arrow = Arrow(dot, string.get_center())
vibration_config = {
"overtones" : 1,
"spatial_period" : 2,
}
vibration, loud_vibration, quiet_vibration = [
Vibrate(string.copy(), amplitude = a, **vibration_config)
for a in [0.5, 1., 0.25]
]
self.add(small_grid)
self.dither()
self.play(
Transform(small_grid, big_grid)
)
self.play(FadeIn(pixel))
self.dither()
self.play(
FadeOut(small_grid),
ShowCreation(freq_line)
)
self.remove(small_grid)
self.play(
Transform(pixel, dot),
)
self.dither()
self.play(ShowCreation(arrow))
self.play(loud_vibration)
self.play(
TransformAnimations(loud_vibration, quiet_vibration),
ApplyMethod(dot.fade, 0.9)
)
self.clear()
self.add(freq_line, dot, arrow)
self.play(quiet_vibration)
class FormalDefinitionOfContinuity(Scene):
def construct(self):
self.setup()
self.label_spaces()
self.move_dot()
self.label_jump()
self.draw_circles()
self.vary_circle_sizes()
self.discontinuous_point()
def setup(self):
self.input_color = YELLOW_C
self.output_color = RED
def spiril(t):
theta = 2*np.pi*t
return t*np.cos(theta)*RIGHT+t*np.sin(theta)*UP
self.spiril1 = ParametricFunction(
lambda t : 1.5*RIGHT + DOWN + 2*spiril(t),
density = 5*DEFAULT_POINT_DENSITY_1D,
)
self.spiril2 = ParametricFunction(
lambda t : 5.5*RIGHT + UP - 2*spiril(1-t),
density = 5*DEFAULT_POINT_DENSITY_1D,
)
Mobject.align_data(self.spiril1, self.spiril2)
self.output = Mobject(self.spiril1, self.spiril2)
self.output.ingest_sub_mobjects()
self.output.highlight(GREEN_A)
self.interval = UnitInterval()
self.interval.scale_to_fit_width(SPACE_WIDTH-1)
self.interval.to_edge(LEFT)
self.input_dot = Dot(color = self.input_color)
self.output_dot = self.input_dot.copy().highlight(self.output_color)
left, right = self.interval.get_left(), self.interval.get_right()
self.input_homotopy = lambda (x, y, z, t) : (x, y, t) + interpolate(left, right, t)
output_size = self.output.get_num_points()-1
output_points = self.output.points
self.output_homotopy = lambda (x, y, z, t) : (x, y, z) + output_points[int(t*output_size)]
def get_circles_and_points(self, min_input, max_input):
input_left, input_right = [
self.interval.number_to_point(num)
for num in min_input, max_input
]
input_circle = Circle(
radius = np.linalg.norm(input_left-input_right)/2,
color = WHITE
)
input_circle.shift((input_left+input_right)/2)
input_points = Line(
input_left, input_right,
color = self.input_color
)
output_points = Mobject(color = self.output_color)
n = self.output.get_num_points()
output_points.add_points(
self.output.points[int(min_input*n):int(max_input*n)]
)
output_center = output_points.points[int(0.5*output_points.get_num_points())]
max_distance = np.linalg.norm(output_center-output_points.points[-1])
output_circle = Circle(
radius = max_distance,
color = WHITE
)
output_circle.shift(output_center)
return (
input_circle,
input_points,
output_circle,
output_points
)
def label_spaces(self):
input_space = TextMobject("Input Space")
input_space.to_edge(UP)
input_space.shift(LEFT*SPACE_WIDTH/2)
output_space = TextMobject("Output Space")
output_space.to_edge(UP)
output_space.shift(RIGHT*SPACE_WIDTH/2)
line = Line(
UP*SPACE_HEIGHT, DOWN*SPACE_HEIGHT,
color = WHITE
)
self.play(
ShimmerIn(input_space),
ShimmerIn(output_space),
ShowCreation(line),
ShowCreation(self.interval),
)
self.dither()
def move_dot(self):
kwargs = {
"rate_func" : None,
"run_time" : 3
}
self.play(
Homotopy(self.input_homotopy, self.input_dot, **kwargs),
Homotopy(self.output_homotopy, self.output_dot, **kwargs),
ShowCreation(self.output, **kwargs)
)
self.dither()
def label_jump(self):
jump_points = Mobject(
Point(self.spiril1.points[-1]),
Point(self.spiril2.points[0])
)
self.brace = Brace(jump_points, RIGHT)
self.jump = TextMobject("Jump")
self.jump.next_to(self.brace, RIGHT)
self.play(
GrowFromCenter(self.brace),
ShimmerIn(self.jump)
)
self.dither()
self.remove(self.brace, self.jump)
def draw_circles(self):
input_value = 0.45
input_radius = 0.04
for dot in self.input_dot, self.output_dot:
dot.center()
kwargs = {
"rate_func" : lambda t : interpolate(1, input_value, smooth(t))
}
self.play(
Homotopy(self.input_homotopy, self.input_dot, **kwargs),
Homotopy(self.output_homotopy, self.output_dot, **kwargs)
)
A, B = map(Mobject.get_center, [self.input_dot, self.output_dot])
A_text = TextMobject("A")
A_text.shift(A+2*(LEFT+UP))
A_arrow = Arrow(
A_text, self.input_dot,
color = self.input_color
)
B_text = TextMobject("B")
B_text.shift(B+2*RIGHT+DOWN)
B_arrow = Arrow(
B_text, self.output_dot,
color = self.output_color
)
tup = self.get_circles_and_points(
input_value-input_radius,
input_value+input_radius
)
input_circle, input_points, output_circle, output_points = tup
for text, arrow in [(A_text, A_arrow), (B_text, B_arrow)]:
self.play(
ShimmerIn(text),
ShowCreation(arrow)
)
self.dither()
self.remove(A_text, A_arrow, B_text, B_arrow)
self.play(ShowCreation(input_circle))
self.dither()
self.play(ShowCreation(input_points))
self.dither()
input_points_copy = input_points.copy()
self.play(
Transform(input_points_copy, output_points),
run_time = 2
)
self.dither()
self.play(ShowCreation(output_circle))
self.dither()
self.dither()
self.remove(*[
input_circle, input_points,
output_circle, input_points_copy
])
def vary_circle_sizes(self):
input_value = 0.45
radius = 0.04
vary_circles = VaryCircles(
self, input_value, radius,
run_time = 5,
)
self.play(vary_circles)
self.dither()
text = TextMobject("Function is ``Continuous at A''")
text.shift(2*UP).to_edge(LEFT)
arrow = Arrow(text, self.input_dot)
self.play(
ShimmerIn(text),
ShowCreation(arrow)
)
self.dither()
self.remove(vary_circles.mobject, text, arrow)
def discontinuous_point(self):
point_description = TextMobject(
"Point where the function jumps"
)
point_description.shift(3*RIGHT)
discontinuous_at_A = TextMobject(
"``Discontinuous at A''",
size = "\\Large"
)
discontinuous_at_A.shift(2*UP).to_edge(LEFT)
text = TextMobject("""
Circle around ouput \\\\
points can never \\\\
be smaller than \\\\
the jump
""")
text.scale(0.75)
text.shift(3.5*RIGHT)
input_value = 0.5
input_radius = 0.04
vary_circles = VaryCircles(
self, input_value, input_radius,
run_time = 5,
)
for dot in self.input_dot, self.output_dot:
dot.center()
kwargs = {
"rate_func" : lambda t : interpolate(0.45, input_value, smooth(t))
}
self.play(
Homotopy(self.input_homotopy, self.input_dot, **kwargs),
Homotopy(self.output_homotopy, self.output_dot, **kwargs)
)
discontinuous_arrow = Arrow(discontinuous_at_A, self.input_dot)
arrow = Arrow(
point_description, self.output_dot,
buff = 0.05,
color = self.output_color
)
self.play(
ShimmerIn(point_description),
ShowCreation(arrow)
)
self.dither()
self.remove(point_description, arrow)
tup = self.get_circles_and_points(
input_value-input_radius,
input_value+input_radius
)
input_circle, input_points, output_circle, output_points = tup
input_points_copy = input_points.copy()
self.play(ShowCreation(input_circle))
self.play(ShowCreation(input_points))
self.play(
Transform(input_points_copy, output_points),
run_time = 2
)
self.play(ShowCreation(output_circle))
self.dither()
self.play(ShimmerIn(text))
self.remove(input_circle, input_points, output_circle, input_points_copy)
self.play(vary_circles)
self.dither()
self.play(
ShimmerIn(discontinuous_at_A),
ShowCreation(discontinuous_arrow)
)
self.dither(3)
self.remove(vary_circles.mobject, discontinuous_at_A, discontinuous_arrow)
def continuous_point(self):
pass