mirror of
https://github.com/3b1b/manim.git
synced 2025-08-01 17:29:06 +08:00
Up to physics example in eola chapter 0
This commit is contained in:
Grant Sanderson
383
eola/chapter0.py
383
eola/chapter0.py
@ -16,6 +16,7 @@ from scene import Scene
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from camera import Camera
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from mobject.svg_mobject import *
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from mobject.tex_mobject import *
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from mobject.vectorized_mobject import *
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from eola.utils import *
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@ -37,22 +38,20 @@ class OpeningQuote(Scene):
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words.to_edge(UP)
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for mob in words.submobjects[48:49+13]:
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mob.highlight(GREEN)
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words.show()
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author = TextMobject("-Hermann Weyl")
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author.highlight(YELLOW)
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author.next_to(words, DOWN)
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self.play(Write(words))
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self.dither()
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self.play(FadeIn(author))
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self.play(FadeIn(words))
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self.dither(3)
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self.play(Write(author))
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self.dither()
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class AboutLinearAlgebra(Scene):
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def construct(self):
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self.show_dependencies()
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self.linalg_is_confusing()
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self.ask_questions()
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self.to_thought_bubble()
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def show_dependencies(self):
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linalg = TextMobject("Linear Algebra")
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@ -86,7 +85,7 @@ class AboutLinearAlgebra(Scene):
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self.dither()
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self.linalg = linalg
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def linalg_is_confusing(self):
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def to_thought_bubble(self):
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linalg = self.linalg
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all_else = list(self.mobjects)
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all_else.remove(linalg)
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@ -94,6 +93,7 @@ class AboutLinearAlgebra(Scene):
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randy.to_corner()
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bubble = randy.get_bubble(width = 10)
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new_linalg = bubble.position_mobject_inside(linalg.copy())
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q_marks = TextMobject("???").next_to(randy, UP)
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self.play(*map(FadeOut, all_else))
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self.remove(*all_else)
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@ -102,17 +102,44 @@ class AboutLinearAlgebra(Scene):
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Write(bubble),
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FadeIn(randy)
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)
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self.play(ApplyMethod(randy.change_mode, "confused"))
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self.dither()
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self.play(Blink(randy))
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self.play(FadeOut(linalg))
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self.remove(linalg)
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self.randy, self.bubble = randy, bubble
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topics = [
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self.get_matrix_multiplication(),
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self.get_determinant(),
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self.get_cross_product(),
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self.get_eigenvalue(),
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]
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questions = [
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self.get_matrix_multiplication_question(),
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self.get_cross_product_question(),
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self.get_eigen_question(),
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]
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for count, topic in enumerate(topics + questions):
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bubble.position_mobject_inside(topic)
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if count == len(topics):
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self.play(FadeOut(linalg))
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self.play(
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ApplyMethod(randy.change_mode, "confused"),
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Write(q_marks, run_time = 1)
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)
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linalg = VectorizedPoint(linalg.get_center())
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if count > len(topics):
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self.remove(linalg)
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self.play(FadeIn(topic))
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linalg = topic
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else:
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self.play(Transform(linalg, topic))
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def ask_questions(self):
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randy, bubble = self.randy, self.bubble
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matrix_multiplication = TexMobject("""
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if count %3 == 0:
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self.play(Blink(randy))
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self.dither()
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else:
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self.dither(2)
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def get_matrix_multiplication(self):
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return TexMobject("""
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\\left[
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\\begin{array}{cc}
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a & b \\\\
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@ -134,6 +161,44 @@ class AboutLinearAlgebra(Scene):
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\\right]
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""")
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def get_determinant(self):
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return TexMobject("""
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\\text{Det}\\left(
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\\begin{array}{cc}
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a & b \\\\
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c & d
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\\end{array}
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\\right)
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=
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ac - bc
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""")
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def get_cross_product(self):
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return TexMobject("""
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\\vec\\textbf{v} \\times \\textbf{w} =
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\\text{Det}\\left(
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\\begin{array}{ccc}
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\\hat{\imath} & \\hat{\jmath} & \\hat{k} \\\\
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v_1 & v_2 & v_3 \\\\
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w_1 & w_2 & w_3 \\\\
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\\end{array}
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\\right)
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""")
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def get_eigenvalue(self):
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result = TextMobject("\\Text{Det}\\left(A - \\lambda I \\right) = 0")
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result.submobjects[-5].highlight(YELLOW)
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return result
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def get_matrix_multiplication_question(self):
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why = TextMobject("Why?").highlight(BLUE)
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mult = self.get_matrix_multiplication()
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why.next_to(mult, UP)
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result = VMobject(why, mult)
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result.get_center = lambda : mult.get_center()
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return result
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def get_cross_product_question(self):
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cross = TexMobject("\\vec{v} \\times \\vec{w}")
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left_right_arrow = DoubleArrow(Point(LEFT), Point(RIGHT))
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det = TextMobject("Det")
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@ -143,19 +208,16 @@ class AboutLinearAlgebra(Scene):
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q_mark.next_to(left_right_arrow, UP)
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cross_question = VMobject(cross, left_right_arrow, q_mark, det)
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cross_question.get_center = lambda : left_right_arrow.get_center()
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return cross_question
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eigen_q = TextMobject("Eigen?")
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for mob in matrix_multiplication, cross_question, eigen_q:
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bubble.position_mobject_inside(mob)
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self.play(FadeIn(mob))
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if randy.mode is not "pondering":
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self.play(ApplyMethod(randy.change_mode, "pondering"))
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self.dither()
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else:
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self.dither(2)
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self.remove(mob)
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def get_eigen_question(self):
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result = TextMobject(
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"What the heck \\\\ does ``eigen'' mean?",
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)
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for mob in result.submobjects[-11:-6]:
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mob.highlight(YELLOW)
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return result
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class NumericVsGeometric(Scene):
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@ -265,11 +327,11 @@ class NumericVsGeometric(Scene):
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class ExampleTransformation(LinearTransformationScene):
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def construct(self):
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self.setup()
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self.add_vector(np.array(TRANFORMED_VECTOR).flatten())
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self.apply_matrix(EXAMPLE_TRANFORM)
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self.dither()
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class NumericToComputations(Scene):
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def construct(self):
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top = TextMobject("Numeric understanding")
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@ -285,6 +347,273 @@ class NumericToComputations(Scene):
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class LinAlgPyramid(Scene):
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def construct(self):
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rects = self.get_rects()
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words = self.place_words_in_rects([
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"Geometric understanding",
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"Computations",
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"Uses"
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], rects)
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for word, rect in zip(words, rects):
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self.play(
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Write(word),
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ShowCreation(rect),
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run_time = 1
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)
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self.dither()
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self.play(*[
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ApplyMethod(m.highlight, DARK_GREY)
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for m in words[0], rects[0]
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])
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self.dither()
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self.list_applications(rects[-1])
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def get_rects(self):
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height = 1
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rects = [
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Rectangle(height = height, width = width)
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for width in 8, 5, 2
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]
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rects[0].shift(2*DOWN)
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for i in 1, 2:
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rects[i].next_to(rects[i-1], UP, buff = 0)
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return rects
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def place_words_in_rects(self, words, rects):
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result = []
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for word, rect in zip(words, rects):
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tex_mob = TextMobject(word)
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tex_mob.shift(rect.get_center())
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result.append(tex_mob)
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return result
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def list_applications(self, top_mob):
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subjects = [
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TextMobject(word).to_corner(UP+RIGHT)
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for word in [
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"computer science",
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"engineering",
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"statistics",
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"economics",
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"pure math",
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]
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]
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arrow = Arrow(top_mob, subjects[0].get_bottom(), color = RED)
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self.play(ShowCreation(arrow))
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curr_subject = None
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for subject in subjects:
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if curr_subject:
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subject.shift(curr_subject.get_center()-subject.get_center())
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self.play(Transform(curr_subject, subject, run_time = 0.5))
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else:
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curr_subject = subject
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self.play(FadeIn(curr_subject, run_time = 0.5))
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self.dither()
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class IndimidatingProf(Scene):
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def construct(self):
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randy = Randolph().to_corner()
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morty = Mortimer().to_corner(DOWN+RIGHT)
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morty.shift(3*LEFT)
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speech_bubble = SpeechBubble(height = 3).flip()
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speech_bubble.pin_to(morty)
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speech_bubble.shift(RIGHT)
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speech_bubble.write("And of course $B^{-1}AB$ will \\\\ also have positive eigenvalues...")
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thought_bubble = ThoughtBubble(width = 4, height = 4)
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thought_bubble.next_to(morty, UP)
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thought_bubble.to_edge(RIGHT)
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q_marks = TextMobject("???")
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q_marks.next_to(randy, UP)
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self.add(randy, morty)
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self.play(
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FadeIn(speech_bubble),
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ApplyMethod(morty.change_mode, "speaking")
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)
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self.play(FadeIn(thought_bubble))
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self.dither()
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self.play(
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ApplyMethod(randy.change_mode, "confused"),
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Write(q_marks, run_time = 1)
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)
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self.dither()
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class ThoughtBubbleTransformation(LinearTransformationScene):
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def construct(self):
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self.setup()
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rotation = rotation_about_z(np.pi/3)
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self.apply_matrix(
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np.linalg.inv(rotation),
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path_arc = -np.pi/3,
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)
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self.apply_matrix(EXAMPLE_TRANFORM)
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self.apply_matrix(
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rotation,
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path_arc = np.pi/3,
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)
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self.dither()
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class SineApproximations(Scene):
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def construct(self):
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series = self.get_series()
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one_approx = self.get_approx_series("1", 1)
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one_approx.highlight(YELLOW)
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pi_sixts_approx = self.get_approx_series("\\pi/6", np.pi/6)
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pi_sixts_approx.highlight(RED)
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words = TextMobject("(How calculators compute sine)")
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words.highlight(GREEN)
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series.to_edge(UP)
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one_approx.next_to(series, DOWN, buff = 1.5)
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pi_sixts_approx.next_to(one_approx, DOWN, buff = 1.5)
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self.play(Write(series))
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self.dither()
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self.play(FadeIn(words))
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self.dither(2)
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self.play(FadeOut(words))
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self.remove(words)
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self.dither()
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self.play(Write(one_approx))
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self.play(Write(pi_sixts_approx))
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self.dither()
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def get_series(self):
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return TexMobject("""
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\\sin(x) = x - \\dfrac{x^3}{3!} + \\dfrac{x^5}{5!}
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+ \\cdots + (-1)^n \\dfrac{x^{2n+1}}{(2n+1)!} + \\cdots
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""")
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def get_approx_series(self, val_str, val):
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#Default to 3 terms
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approximation = val - (val**3)/6. + (val**5)/120.
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return TexMobject("""
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\\sin(%s) \\approx
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%s - \\dfrac{(%s)^3}{3!} + \\dfrac{(%s)^5}{5!} \\approx
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%.04f
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"""%(val_str, val_str, val_str, val_str, approximation))
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class LooseConnectionToTriangles(Scene):
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def construct(self):
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sine = TexMobject("\\sin(x)")
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triangle = Polygon(ORIGIN, 2*RIGHT, 2*RIGHT+UP)
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arrow = DoubleArrow(LEFT, RIGHT)
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sine.next_to(arrow, LEFT)
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triangle.next_to(arrow, RIGHT)
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q_mark = TextMobject("?").scale(1.5)
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q_mark.next_to(arrow, UP)
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self.add(sine)
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self.play(ShowCreation(arrow))
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self.play(ShowCreation(triangle))
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self.play(Write(q_mark))
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self.dither()
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class PhysicsExample(Scene):
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def construct(self):
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title = TextMobject("Physics")
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title.to_corner(UP+LEFT)
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parabola = FunctionGraph(
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lambda x : (3-x)*(3+x)/4,
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x_min = -4,
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x_max = 4
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)
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self.play(Write(title))
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self.projectile(parabola)
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self.velocity_vector(parabola)
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self.approximate_sine()
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def projectile(self, parabola):
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dot = Dot(radius = 0.15)
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kwargs = {
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"run_time" : 3,
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"rate_func" : None
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}
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self.play(
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MoveAlongPath(dot, parabola.copy(), **kwargs),
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ShowCreation(parabola, **kwargs)
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)
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self.dither()
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def velocity_vector(self, parabola):
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alpha = 0.7
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d_alpha = 0.01
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vector_length = 3
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p1 = parabola.point_from_proportion(alpha)
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p2 = parabola.point_from_proportion(alpha + d_alpha)
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vector = vector_length*(p2-p1)/np.linalg.norm(p2-p1)
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v_mob = Vector(vector, color = YELLOW)
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vx = Vector(vector[0]*RIGHT, color = GREEN_B)
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vy = Vector(vector[1]*UP, color = RED)
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v_mob.shift(p1)
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vx.shift(p1)
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vy.shift(vx.get_end())
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arc = Arc(
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angle_of_vector(vector),
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radius = vector_length / 4.
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)
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arc.shift(p1)
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theta = TexMobject("\\theta").scale(0.75)
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theta.next_to(arc, RIGHT, buff = 0.1)
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v_label = TexMobject("\\vec{v}")
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v_label.shift(p1 + RIGHT*vector[0]/4 + UP*vector[1]/2)
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v_label.highlight(v_mob.get_color())
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vx_label = TexMobject("\\vec{v} \\cos(\\theta)")
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vx_label.next_to(vx, UP)
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vx_label.highlight(vx.get_color())
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vy_label = TexMobject("\\vec{v} \\sin(\\theta)")
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vy_label.next_to(vy, RIGHT)
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vy_label.highlight(vy.get_color())
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kwargs = {"submobject_mode" : "one_at_a_time"}
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for v in v_mob, vx, vy:
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self.play(
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ShowCreation(v, submobject_mode = "one_at_a_time")
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)
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self.play(
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ShowCreation(arc),
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Write(theta, run_time = 1)
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)
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for label in v_label, vx_label, vy_label:
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self.play(Write(label, run_time = 1))
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self.dither()
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def approximate_sine(self):
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approx = TexMobject("\\sin(\\theta) \\approx 0.7\\text{-ish}")
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morty = Mortimer(mode = "speaking")
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morty.flip()
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morty.to_corner()
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bubble = SpeechBubble(width = 4, height = 3)
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bubble.set_fill(BLACK, opacity = 1)
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bubble.pin_to(morty)
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bubble.position_mobject_inside(approx)
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self.play(
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FadeIn(morty),
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ShowCreation(bubble),
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Write(approx),
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run_time = 2
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)
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self.dither()
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class LinearAlgebraIntuitions(Scene):
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def construct(self):
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pass
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Reference in New Issue
Block a user