Start of chapter 10

This commit is contained in:
Grant Sanderson
2016-09-10 17:35:15 -07:00
parent c2301e282c
commit 0df8b73a87
4 changed files with 247 additions and 49 deletions

View File

@ -65,9 +65,9 @@ class Write(ShowCreation):
mobject = TextMobject(mob_or_text)
else:
mobject = mob_or_text
if not hasattr(self, "run_time"):
if "run_time" not in kwargs:
self.establish_run_time(mobject)
if not hasattr(self, "lag_factor"):
if "lag_factor" not in kwargs:
self.lag_factor = self.run_time - 1
ShowCreation.__init__(self, mobject, **kwargs)

View File

@ -41,12 +41,247 @@ class OpeningQuote(Scene):
author.highlight(YELLOW)
author.next_to(words, DOWN, buff = 0.5)
self.play(Write(words, run_time = 8))
self.dither(2)
self.play(Write(author, run_time = 3))
self.dither(2)
self.play(Write(words, run_time = 10))
self.dither()
self.play(FadeIn(author))
self.dither(3)
class NewSceneName(Scene):
class StudentsFindThisConfusing(TeacherStudentsScene):
def construct(self):
title = TextMobject("Eigenvectors and Eigenvalues")
title.to_edge(UP)
students = self.get_students()
self.play(
Write(title),
*[
ApplyMethod(pi.look_at, title)
for pi in self.get_everyone()
]
)
self.play(
self.get_teacher().look_at, students[-1].eyes,
students[0].change_mode, "confused",
students[1].change_mode, "tired",
students[2].change_mode, "sassy",
)
self.random_blink()
self.student_says(
"Why are we doing this?",
student_index = 0,
run_time = 2,
)
question1 = students[0].bubble.content.copy()
self.student_says(
"What does this actually mean?",
student_index = 2,
added_anims = [
question1.scale_in_place, 0.8,
question1.to_edge, LEFT,
question1.shift, DOWN,
]
)
question2 = students[2].bubble.content.copy()
question2.target = question2.copy()
question2.target.next_to(
question1, DOWN,
aligned_edge = LEFT,
buff = MED_BUFF
)
equation = TexMobject(
"\\det\\left( %s \\right)=0"%matrix_to_tex_string([
["a-\\lambda", "b"],
["c", "d-\\lambda"],
])
)
equation.highlight(YELLOW)
self.teacher_says(
equation,
added_anims = [MoveToTarget(question2)]
)
self.change_student_modes(*["confused"]*3)
self.random_blink(3)
class ShowComments(Scene):
pass
class EigenThingsArentAllThatBad(TeacherStudentsScene):
def construct(self):
self.teacher_says(
"Eigen-things aren't \\\\ actually so bad",
pi_creature_target_mode = "hooray"
)
self.random_blink(5)
class ManyPrerequisites(Scene):
def construct(self):
title = TextMobject("Many prerequisites")
title.to_edge(UP)
h_line = Line(LEFT, RIGHT).scale(SPACE_WIDTH)
h_line.next_to(title, DOWN)
self.add(title)
self.play(ShowCreation(h_line))
rect = Rectangle(height = 9, width = 16, color = BLUE)
rect.scale_to_fit_width(SPACE_WIDTH-2)
rects = [rect]+[rect.copy() for i in range(3)]
words = [
"Linear transformations",
"Determinants",
"Linear systems",
"Change of basis",
]
for rect, word in zip(rects, words):
word_mob = TextMobject(word)
word_mob.next_to(rect, UP, buff = MED_BUFF)
rect.add(word_mob)
Matrix(np.array(rects).reshape((2, 2)))
rects = VGroup(*rects)
rects.scale_to_fit_height(2*SPACE_HEIGHT - 1.5)
rects.next_to(h_line, DOWN, buff = MED_BUFF)
self.play(Write(rects[0]))
self.dither()
self.play(*map(FadeIn, rects[1:]))
self.dither()
class ExampleTranformationScene(LinearTransformationScene):
CONFIG = {
"t_matrix" : [[3, 0], [1, 2]]
}
def setup(self):
LinearTransformationScene.setup(self)
self.add_matrix()
def add_matrix(self):
matrix = Matrix(self.t_matrix.T)
matrix.highlight_columns(X_COLOR, Y_COLOR)
matrix.next_to(ORIGIN, LEFT, buff = MED_BUFF)
matrix.to_edge(UP)
matrix.rect = BackgroundRectangle(matrix)
matrix.add_to_back(matrix.rect)
self.add_foreground_mobject(matrix)
self.matrix = matrix
def remove_matrix(self):
self.remove(self.matrix)
self.foreground_mobjects.remove(self.matrix)
class IntroduceExampleTransformation(ExampleTranformationScene):
def construct(self):
self.remove_matrix()
i_coords = Matrix(self.t_matrix[0])
j_coords = Matrix(self.t_matrix[1])
self.apply_transposed_matrix(self.t_matrix)
for coords, vect in (i_coords, self.i_hat), (j_coords, self.j_hat):
coords.highlight(vect.get_color())
coords.scale(0.8)
coords.rect = BackgroundRectangle(coords)
coords.add_to_back(coords.rect)
coords.next_to(vect.get_end(), RIGHT)
self.play(Write(coords))
self.dither()
i_coords_copy = i_coords.copy()
self.play(*[
Transform(*pair)
for pair in [
(i_coords_copy.rect, self.matrix.rect),
(i_coords_copy.get_brackets(), self.matrix.get_brackets()),
(
i_coords_copy.get_entries(),
VGroup(*self.matrix.get_mob_matrix()[:,0])
)
]
])
self.play(Transform(
j_coords.copy().get_entries(),
VGroup(*self.matrix.get_mob_matrix()[:,1])
))
self.dither()
class VectorKnockedOffSpan(ExampleTranformationScene):
def construct(self):
vector = Vector([2, 1])
line = Line(vector.get_end()*-4, vector.get_end()*4, color = MAROON_B)
vector.scale(0.7)
top_words, off, span_label = all_words = TextMobject(
"\\centering Vector gets knocked", "\\\\ off", "Span"
)
all_words.shift(
line.point_from_proportion(0.75) - \
span_label.get_corner(DOWN+RIGHT) + \
MED_BUFF*LEFT
)
for text in all_words:
text.add_to_back(BackgroundRectangle(text))
self.add_vector(vector)
self.dither()
self.play(
ShowCreation(line),
Write(span_label),
Animation(vector),
)
self.add_foreground_mobject(span_label)
self.dither()
self.apply_transposed_matrix(self.t_matrix)
self.play(Animation(span_label.copy()), Write(all_words))
self.dither()
class VectorRemainsOnSpan(ExampleTranformationScene):
def construct(self):
vector = Vector([1, -1])
v_end = vector.get_end()
line = Line(-4*v_end, 4*v_end, color = MAROON_B)
words = TextMobject("Vector remains on", "\\\\its own span")
words.next_to(ORIGIN, DOWN+LEFT)
for part in words:
part.add_to_back(BackgroundRectangle(part))
self.add_vector(vector)
self.play(ShowCreation(line), Animation(vector))
self.dither()
self.apply_transposed_matrix(self.t_matrix)
self.play(Write(words))
self.dither()
target_vectors = [
vector.copy().scale(scalar)
for scalar in 2, -2, 1
]
for target, time in zip(target_vectors, [1, 2, 2]):
self.play(Transform(vector, target, run_time = time))
self.dither()
class IHatAsEigenVector(ExampleTranformationScene):
def construct(self):
# self.highlight_first_column()
def homotopy(x, y, z, t):
pass
x_axis = self.plane.axes[0]
self.play(
x_axis.highlight, GREEN_E,
Homotopy(plane_wave_homotopy, x_axis, run_time = 3)
)
def highlight_first_column(self):
faders = VGroup(self.plane, self.i_hat, self.j_hat)
faders.save_state()
column1 = VGroup(*self.matrix.get_mob_matrix()[:,0])
self.play(faders.fade, 0.7, Animation(self.matrix))
self.play(column1.scale_in_place, 1.3, rate_func = there_and_back)
self.dither()
self.play(faders.restore, Animation(self.matrix))
self.dither()
class SneakierEigenVector(ExampleTranformationScene):
def construct(self):
pass
class NameEigenvectorsAndEigenvalues(ExampleTranformationScene):
def construct(self):
pass
@ -65,21 +300,6 @@ class NewSceneName(Scene):

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@ -38,6 +38,7 @@ class TexMobject(SVGMobject):
"initial_scale_factor" : TEX_MOB_SCALE_FACTOR,
"organize_left_to_right" : False,
"propogate_style_to_family" : True,
"alignment" : "",
}
def __init__(self, *args, **kwargs):
digest_config(self, kwargs, locals())
@ -72,6 +73,8 @@ class TexMobject(SVGMobject):
result = self.arg_separator.join(self.args)
if self.enforce_new_line_structure:
result = result.replace("\n", " \\\\ \n ")
result = " ".join([self.alignment, result])
result = result.strip()
return result
def get_tex_string(self):
@ -120,6 +123,7 @@ class TextMobject(TexMobject):
"template_tex_file" : TEMPLATE_TEXT_FILE,
"initial_scale_factor" : TEXT_MOB_SCALE_FACTOR,
"enforce_new_line_structure" : True,
"alignment" : "\\centering",
}

View File

@ -115,6 +115,7 @@ class PiCreature(SVGMobject):
else:
point = point_or_mobject
self.look(point - self.eyes.get_center())
return self
def get_looking_direction(self):
@ -176,33 +177,6 @@ class Blink(ApplyMethod):
def __init__(self, pi_creature, **kwargs):
ApplyMethod.__init__(self, pi_creature.blink, **kwargs)
class DoTheWave(Transform):
CONFIG = {
"run_time" : 2
}
def __init__(self, pi_creature, **kwargs):
start_state = pi_creature.copy()
self.target_states = [
pi_creature.copy().change_mode("wave_%d"%x)
for x in 1, 2, 3
] + [
pi_creature.copy()
]
Transform.__init__(self, pi_creature, self.target_states[0], **kwargs)
def update_mobject(self, alpha):
scaled = alpha*len(self.target_states)
try:
if scaled-1 > 0:
self.starting_mobject = self.target_states[int(scaled)-1]
self.ending_mobject = self.target_states[int(scaled)]
except IndexError:
self.ending_mobject = self.target_states[-1]
Transform.update_mobject(self, scaled%1)
return self
class Bubble(SVGMobject):