Changes to basel, and replication of the file

active_projects/basel.py

@@ -247,9 +247,10 @@ class ThinkAboutPondScene(PiCreatureScene):
 class IntroScene(PiCreatureScene):
 
     CONFIG = {
-        "rect_height" : 0.2,
+        "rect_height" : 0.1,
         "duration" : 1.0,
-        "eq_spacing" : 3 * MED_LARGE_BUFF
+        "eq_spacing" : 3 * MED_LARGE_BUFF,
+        "n_rects_to_show" : 30,
     }
 
     def construct(self):
@@ -257,12 +258,12 @@ class IntroScene(PiCreatureScene):
         randy.scale(0.7).to_corner(DOWN+RIGHT)
 
         self.build_up_euler_sum()
-        self.show_pi_answer()
-        self.other_pi_formulas()
-        self.refocus_on_euler_sum()
-
+        self.show_history()
+        # self.other_pi_formulas()
+        # self.refocus_on_euler_sum()
 
     def build_up_euler_sum(self):
+        morty = self.pi_creature
         euler_sum = self.euler_sum = TexMobject(
            "1", "+", 
            "{1 \\over 4}", "+",
@@ -273,24 +274,26 @@ class IntroScene(PiCreatureScene):
             arg_separator = " \\, "
         )
         equals_sign = euler_sum.get_part_by_tex("=")
+        plusses = euler_sum.get_parts_by_tex("+")
+        term_mobjects = euler_sum.get_parts_by_tex("1")
 
         self.euler_sum.to_edge(UP)
         self.euler_sum.shift(2*LEFT)
        
-        terms = [1./n**2 for n in range(1,100)]
-        partial_results_values = np.cumsum(terms)
+        max_n = self.n_rects_to_show
+        terms = [1./(n**2) for n in range(1, max_n + 1)]
+        series_terms = list(np.cumsum(terms))
+        series_terms.append(np.pi**2/6) ##Just force this up there
 
-        self.play(FadeIn(euler_sum[0]))
-
-        equals_sign = self.euler_sum.get_part_by_tex("=")
-
-        self.partial_sum_decimal = DecimalNumber(partial_results_values[1],
-                num_decimal_points = 2)
-        self.partial_sum_decimal.next_to(equals_sign, RIGHT)
+        partial_sum_decimal = self.partial_sum_decimal = DecimalNumber(
+            series_terms[1],
+            num_decimal_points = 2
+        )
+        partial_sum_decimal.next_to(equals_sign, RIGHT)
 
         ## Number line
 
-        self.number_line = NumberLine(
+        number_line = self.number_line = NumberLine(
             x_min = 0,
             color = WHITE,
             number_at_center = 1,
@@ -301,105 +304,214 @@ class IntroScene(PiCreatureScene):
             tick_frequency = 0.2,
             line_to_number_buff = MED_LARGE_BUFF
         )
-
-        self.number_line_labels = self.number_line.get_number_mobjects()
-        self.add(self.number_line,self.number_line_labels)
-        self.wait()
+        number_line.add_numbers()
+        number_line.to_edge(LEFT)
+        number_line.shift(MED_LARGE_BUFF*UP)
 
         # create slabs for series terms
 
-        max_n = 10
-
-        terms = [0] + [1./(n**2) for n in range(1, max_n + 1)]
-        series_terms = np.cumsum(terms)
         lines = VGroup()
-        self.rects = VGroup()
-        slab_colors = [YELLOW, BLUE] * (max_n / 2)
+        rects = self.rects = VGroup()
+        rect_labels = VGroup()
+        slab_colors = it.cycle([YELLOW, BLUE])
+        rect_anims = []
+        rect_label_anims = []
 
-        for t1, t2, color in zip(series_terms, series_terms[1:], slab_colors):
-            line = Line(*map(self.number_line.number_to_point, [t1, t2]))
-            rect = Rectangle()
-            rect.stroke_width = 0
-            rect.fill_opacity = 1
-            rect.highlight(color)
-            rect.stretch_to_fit_height(
-                self.rect_height,
+        for i, t1, t2 in zip(it.count(1), [0]+series_terms, series_terms):
+            color = slab_colors.next()
+            line = Line(*map(number_line.number_to_point, [t1, t2]))
+            rect = Rectangle(
+                stroke_width = 0,
+                fill_opacity = 1,
+                fill_color = color
             )
-            rect.stretch_to_fit_width(line.get_width())
+            rect.match_width(line)
+            rect.stretch_to_fit_height(self.rect_height)
             rect.move_to(line)
 
-            self.rects.add(rect)
-            lines.add(line)
+            if i <= 5:
+                if i == 1:
+                    rect_label = TexMobject("1")
+                else:
+                    rect_label = TexMobject("\\frac{1}{%d}"%(i**2))
+                rect_label.scale(0.75)
+                max_width = 0.7*rect.get_width()
+                if rect_label.get_width() > max_width:
+                    rect_label.scale_to_fit_width(max_width)
+                rect_label.next_to(rect, UP, MED_SMALL_BUFF/(i+1))
 
-        #self.rects.radial_gradient_highlight(ORIGIN, 5, YELLOW, BLUE)
-        
-        for i in range(5):
-            self.play(
-                GrowFromPoint(self.rects[i], self.euler_sum[2*i].get_center(),
-                    run_time = self.duration)
-            )
-
-        for i in range(5, max_n):
-            self.play(
-                GrowFromPoint(self.rects[i], self.euler_sum[10].get_center(),
-                    run_time = self.duration)
-            )
-
-
-        ##
-
-
-        for i in range(4):
-
-            FadeIn(self.partial_sum_decimal, run_time = self.duration)
-
-            if i == 0:
-
-                self.play(
-                    FadeIn(self.euler_sum[1], run_time = self.duration),
-                    FadeIn(self.euler_sum[2], run_time = self.duration),
-                    FadeIn(equals_sign, run_time = self.duration),
-                    FadeIn(self.partial_sum_decimal, run_time = self.duration)
+                term_mobject = term_mobjects[i-1]
+                rect_anim = GrowFromPoint(rect, term_mobject.get_center())
+                rect_label_anim = ReplacementTransform(
+                    term_mobject.copy(), rect_label
                 )
-
             else:
-                self.play(
-                    FadeIn(self.euler_sum[2*i+1], run_time = self.duration),
-                    FadeIn(self.euler_sum[2*i+2], run_time = self.duration),
+                rect_label = VectorizedPoint()
+                rect_anim = GrowFromPoint(rect, rect.get_left())
+                rect_label_anim = FadeIn(rect_label)
+
+            rects.add(rect)
+            rect_labels.add(rect_label)
+            rect_anims.append(rect_anim)
+            rect_label_anims.append(rect_label_anim)
+            lines.add(line)
+        dots = TexMobject("\\dots").scale(0.5)
+        last_rect = rect_anims[-1].target_mobject
+        dots.scale_to_fit_width(0.9*last_rect.get_width())
+        dots.move_to(last_rect, UP+RIGHT)
+        rects.submobjects[-1] = dots
+        rect_anims[-1] = FadeIn(dots)
+
+        self.add(number_line)
+        self.play(FadeIn(euler_sum[0]))
+        self.play(
+            rect_anims[0],
+            rect_label_anims[0]
+        )
+        for i in range(4):
+            self.play(
+                FadeIn(term_mobjects[i+1]),
+                FadeIn(plusses[i]),
+            )
+            anims = [
+                rect_anims[i+1],
+                rect_label_anims[i+1],
+            ]
+            if i == 0:
+                anims += [
+                    FadeIn(equals_sign),
+                    FadeIn(partial_sum_decimal)
+                ]
+            elif i <= 5:
+                anims += [
                     ChangeDecimalToValue(
-                        self.partial_sum_decimal,
-                        partial_results_values[i+1], 
-                        run_time = self.duration,
+                        partial_sum_decimal,
+                        series_terms[i+1], 
+                        run_time = 1,
                         num_decimal_points = 6,
-                        show_ellipsis = True,
                         position_update_func = lambda m: m.next_to(equals_sign, RIGHT)
                     )
-                )
-                
-            self.wait()
+                ]
+            self.play(*anims)
 
-        self.q_marks = TextMobject("???").highlight(LIGHT_COLOR)
-        self.q_marks.move_to(self.partial_sum_decimal)
+        for i in range(4, len(series_terms)-2):
+            anims = [
+                rect_anims[i+1],
+                ChangeDecimalToValue(
+                    partial_sum_decimal,
+                    series_terms[i+1],
+                    num_decimal_points = 6,
+                ),
+            ]
+            if i == 5:
+                anims += [
+                    FadeIn(euler_sum[-3]), # +
+                    FadeIn(euler_sum[-2]), # ...
+                ]
+            self.play(*anims, run_time = 2./i)
+
+        brace = self.brace = Brace(partial_sum_decimal, DOWN)
+        q_marks = self.q_marks = TextMobject("???")
+        q_marks.next_to(brace, DOWN)
+        q_marks.highlight(LIGHT_COLOR)
 
         self.play(
-            FadeIn(self.euler_sum[-3], run_time = self.duration), # +
-            FadeIn(self.euler_sum[-2], run_time = self.duration), # ...
-            ReplacementTransform(self.partial_sum_decimal, self.q_marks)
+            GrowFromCenter(brace),
+            Write(q_marks),
+            ChangeDecimalToValue(
+                partial_sum_decimal,
+                series_terms[-1],
+                num_decimal_points = 6,
+            ),
+            morty.change, "confused",
+        )
+        self.wait()
+
+        self.number_line_group = VGroup(
+            number_line, rects, rect_labels
         )
 
-    def show_pi_answer(self):
+    def show_history(self):
+        # Pietro Mengoli in 1644
+        morty = self.pi_creature
+        pietro = ImageMobject("Pietro_Mengoli")
+        euler = ImageMobject("Euler")
 
-        self.pi_answer = TexMobject("{\\pi^2 \\over 6}").highlight(YELLOW)
-        self.pi_answer.move_to(self.partial_sum_decimal)
-        self.pi_answer.next_to(self.euler_sum[-1], RIGHT,
-            submobject_to_align = self.pi_answer[-2])
-        self.play(ReplacementTransform(self.q_marks, self.pi_answer))
+        pietro_words = TextMobject("Challenge posed by \\\\ Pietro Mengoli in 1644")
+        pietro_words.scale(0.75)
+        pietro_words.next_to(pietro, DOWN)
+        pietro.add(pietro_words)
+
+        euler_words = TextMobject("Solved by Leonard \\\\ Euler in 1735")
+        euler_words.scale(0.75)
+        euler_words.next_to(euler, DOWN)
+        euler.add(euler_words)
+
+        pietro.next_to(SPACE_WIDTH*LEFT, LEFT)
+        euler.next_to(SPACE_WIDTH*RIGHT, RIGHT)
+
+        pi_answer = self.pi_answer = TexMobject("{\\pi^2 \\over 6}")
+        pi_answer.highlight(YELLOW)
+        pi_answer.move_to(self.partial_sum_decimal, LEFT)
+        equals_sign = TexMobject("=")
+        equals_sign.next_to(pi_answer, RIGHT)
+        pi_answer.shift(SMALL_BUFF*UP)
+        self.partial_sum_decimal.generate_target()
+        self.partial_sum_decimal.target.next_to(equals_sign, RIGHT)
+
+        pi = pi_answer[0]
+        pi_rect = SurroundingRectangle(pi, color = RED)
+        pi_rect.save_state()
+        pi_rect.scale_to_fit_height(SPACE_HEIGHT)
+        pi_rect.center()
+        pi_rect.set_stroke(width = 0)
+        squared = pi_answer[1]
+        squared_rect = SurroundingRectangle(squared, color = BLUE)
+
+        brace = Brace(
+            VGroup(self.euler_sum, self.partial_sum_decimal.target),
+            DOWN, buff = SMALL_BUFF
+        )
+        basel_text = brace.get_text("Basel problem", buff = SMALL_BUFF)
+
+        self.number_line_group.save_state()
+        self.play(
+            pietro.next_to, ORIGIN, LEFT, LARGE_BUFF,
+            self.number_line_group.next_to, SPACE_HEIGHT*DOWN, DOWN,
+            morty.change, "pondering",
+        )
+        self.wait(2)
+        self.play(euler.next_to, ORIGIN, RIGHT, LARGE_BUFF)
+        self.wait(2)
+        self.play(
+            ReplacementTransform(self.q_marks, pi_answer),
+            FadeIn(equals_sign),
+            FadeOut(self.brace),
+            MoveToTarget(self.partial_sum_decimal)
+        )
+        self.wait()
+        self.play(morty.change, "surprised")
+        self.play(pi_rect.restore)
+        self.wait()
+        self.play(Transform(pi_rect, squared_rect))
+        self.play(FadeOut(pi_rect))
+        self.play(morty.change, "hesitant")
+        self.wait(2)
+        self.play(
+            GrowFromCenter(brace),
+            euler.to_edge, DOWN,
+            pietro.to_edge, DOWN,
+            self.number_line_group.restore,
+            self.number_line_group.shift, LARGE_BUFF*RIGHT,
+        )
+        self.play(Write(basel_text))
+        self.play(morty.change, "happy")
+        self.wait(4)
 
     def other_pi_formulas(self):
 
         self.play(
             FadeOut(self.rects),
-            FadeOut(self.number_line_labels),
             FadeOut(self.number_line)
         )
 
@@ -468,6 +580,195 @@ class IntroScene(PiCreatureScene):
 
         self.wait()
 
+class PiHidingWrapper(Scene):
+    def construct(self):
+        title = TextMobject("Pi hiding in prime regularities")
+        title.to_edge(UP)
+        screen = ScreenRectangle(height = 6)
+        screen.next_to(title, DOWN)
+        self.add(title)
+        self.play(ShowCreation(screen))
+        self.wait(2)
+
+class MathematicalWebOfConnections(PiCreatureScene):
+    def construct(self):
+        self.complain_that_pi_is_not_about_circles()
+        self.show_other_pi_formulas()
+        self.question_fundamental()
+        self.draw_circle()
+        self.remove_all_but_basel_sum()
+        self.show_web_of_connections()
+        self.show_light()
+
+    def complain_that_pi_is_not_about_circles(self):
+        jerk, randy = self.pi_creatures
+
+        words = self.words = TextMobject(
+            "$\\pi$ is not",
+            "fundamentally \\\\", 
+            "about circles"
+        )
+        words.highlight_by_tex("fundamentally", YELLOW)
+
+        self.play(PiCreatureSays(
+            jerk, words,
+            target_mode = "angry"
+        ))
+        self.play(randy.change, "guilty")
+        self.wait(2)
+
+    def show_other_pi_formulas(self):
+        jerk, randy = self.pi_creatures
+        words = self.words
+
+        basel_sum = TexMobject(
+            "1 + {1 \\over 4} + {1 \\over 9} + {1 \\over 16} + \\cdots", 
+            "=", "{\\pi^2 \\over 6}"
+        )
+        leibniz_sum = TexMobject(
+            "1-{1\\over 3}+{1\\over 5}-{1\\over 7}+{1\\over 9}-\\cdots",
+            "=", "{\\pi \\over 4}")
+
+        wallis_product = TexMobject(
+            "{2\\over 1} \\cdot {2\\over 3} \\cdot {4\\over 3} \\cdot {4\\over 5}" +
+             "\\cdot {6\\over 5} \\cdot {6\\over 7} \\cdots",
+             "=", "{\\pi \\over 2}")
+
+        basel_sum.move_to(randy)
+        basel_sum.to_edge(UP)
+        basel_equals = basel_sum.get_part_by_tex("=")
+
+        formulas = VGroup(basel_sum, leibniz_sum, wallis_product)
+        formulas.scale(0.75)
+        formulas.arrange_submobjects(DOWN, buff = MED_LARGE_BUFF)
+        for formula in formulas:
+            basel_equals_x = basel_equals.get_center()[0]
+            formula_equals_x = formula.get_part_by_tex("=").get_center()[0]
+            formula.shift((basel_equals_x - formula_equals_x)*RIGHT)
+
+        formulas.move_to(randy)
+        formulas.to_edge(UP)
+        formulas.shift_onto_screen()
+        self.formulas = formulas
+
+        self.play(
+            jerk.change, "sassy",
+            randy.change, "raise_right_hand",
+            FadeOut(jerk.bubble),
+            words.next_to, jerk, UP,
+            FadeIn(basel_sum, submobject_mode = "lagged_start", run_time = 3)
+        )
+        for formula in formulas[1:]:
+            self.play(
+                FadeIn(
+                    formula, 
+                    submobject_mode = "lagged_start", 
+                    run_time = 3
+                ),
+            )
+        self.wait()
+
+    def question_fundamental(self):
+        jerk, randy = self.pi_creatures
+        words = self.words
+        fundamentally = words.get_part_by_tex("fundamentally")
+        words.remove(fundamentally)
+
+        self.play(
+            fundamentally.move_to, self.pi_creatures,
+            fundamentally.shift, UP,
+            FadeOut(words),
+            jerk.change, "pondering",
+            randy.change, "pondering",
+        )
+        self.wait()
+
+        question = TextMobject("Does this mean \\\\ anything?")
+        question.scale(0.8)
+        question.set_stroke(WHITE, 0.5)
+        question.next_to(fundamentally, DOWN, LARGE_BUFF)
+        arrow = Arrow(question, fundamentally)
+        arrow.highlight(WHITE)
+
+        self.play(
+            FadeIn(question),
+            GrowArrow(arrow)
+        )
+        self.wait()
+
+        fundamentally.add(question, arrow)
+        self.fundamentally = fundamentally
+
+    def draw_circle(self):
+        semi_circle = Arc(angle = np.pi, radius = 2)
+        radius = Line(ORIGIN, semi_circle.points[0])
+        radius.highlight(BLUE)
+        semi_circle.highlight(YELLOW)
+
+        VGroup(radius, semi_circle).move_to(
+            SPACE_WIDTH*LEFT/2 + SPACE_HEIGHT*UP/2,
+        )
+
+        decimal = DecimalNumber(0)
+        def decimal_position_update_func(decimal):
+            decimal.move_to(semi_circle.points[-1])
+            decimal.shift(0.3*radius.get_vector())
+
+        one = TexMobject("1")
+        one.next_to(radius, UP)
+
+        self.play(ShowCreation(radius), FadeIn(one))
+        self.play(
+            Rotate(radius, np.pi, about_point = radius.get_start()),
+            ShowCreation(semi_circle),
+            ChangeDecimalToValue(
+                decimal, np.pi, 
+                position_update_func = decimal_position_update_func
+            ),
+            MaintainPositionRelativeTo(one, radius),
+            run_time = 3,
+        )
+        self.wait(2)
+
+        self.circle_group = VGroup(semi_circle, radius, one, decimal)
+
+    def remove_all_but_basel_sum(self):
+        to_shift_down = VGroup(
+            self.circle_group, self.pi_creatures,
+            self.fundamentally, self.formulas[1:],
+        )
+        to_shift_down.generate_target()
+        for part in to_shift_down.target:
+            part.move_to(2*SPACE_HEIGHT*DOWN)
+
+        basel_sum = self.formulas[0]
+
+        self.play(
+            MoveToTarget(to_shift_down),
+            basel_sum.scale, 1.5,
+            basel_sum.move_to, 2*DOWN,
+        )
+
+    def show_web_of_connections(self):
+        pass
+
+    def show_light(self):
+        pass
+
+    ###
+
+    def create_pi_creatures(self):
+        jerk = PiCreature(color = GREEN_D)
+        randy = Randolph().flip()
+        jerk.move_to(0.5*SPACE_WIDTH*LEFT).to_edge(DOWN)
+        randy.move_to(0.5*SPACE_WIDTH*RIGHT).to_edge(DOWN)
+
+        return VGroup(jerk, randy)
+
+
+
+
+
 class FirstLighthouseScene(PiCreatureScene):
 
     def construct(self):