2020年5月27日水曜日


代数への出発
楽天ブックス Yahoo!

学習環境

代数への出発 (新装版 数学入門シリーズ) (松坂 和夫(著)、岩波書店)の第6章(1次方程式、2次方程式)、3(1次関数とそのグラフ)問7の解答を求めてみる。



    1. y = x - 1 = { - x + 1 x ≤ 1 x - 1 x ≥ 1

      グラフ。


    2. y = x - 1 + x + 1 = { - x + 1 - x - 1 x ≤ - 1 - x + 1 + x + 1 - 1 ≤ x ≤ 1 x - 1 + x + 1 1 ≥ x = { - 2 x x ≤ - 1 2 - 1 ≤ x ≤ 1 2 x 1 ≥ x

      グラフ。


    3. y = x + x 2 = { - x + x 2 x ≤ 0 x + x 2 x ≥ 0 = { 0 x ≤ 0 x x ≥ 0

      グラフ。


    4. y = x - 1 + 2 x + 4 - 2 x - 4 = { - x + 1 - 2 x - 4 + 2 x - 4 x ≤ - 2 - x + 1 + 2 x + 4 + 2 x - 4 - 2 ≤ x ≤ 1 x - 1 + 2 x + 4 + 2 x - 4 1 ≤ x ≤ 2 x - 1 + 2 x + 4 - 2 x + 4 x ≥ 2 = { - x - 7 x ≤ - 2 3 x + 1 - 2 ≤ x ≤ 1 5 x - 1 1 ≤ x ≤ 2 x + 7 x ≥ 2

      グラフ。

コード

#!/usr/bin/env python3
from sympy import symbols, plot

print('7.')
x = symbols('x')


p = plot(abs(x - 1),
         abs(x - 1) + abs(x + 1),
         (abs(x) + x) / 2,
         abs(x - 1) + abs(2 * x + 4) - abs(2 * x - 4),
         (x, -10, 10),
         ylim=(-10, 10),
         legend=True,
         show=False)

colors = ['red', 'green', 'blue', 'brown', 'orange',
          'purple', 'pink', 'gray', 'skyblue', 'yellow']

for o, color in zip(p, colors):
    o.line_color = color

p.show()
p.save('sample7.png')

入出力結果(Zsh、PowerShell、Terminal、Jupyter(IPython))

% ./sample7.py
7.
/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/sympy/plotting/plot.py:1065: MatplotlibDeprecationWarning: 
The set_smart_bounds function was deprecated in Matplotlib 3.2 and will be removed two minor releases later.
  self.ax[i].spines['left'].set_smart_bounds(True)
/opt/local/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/sympy/plotting/plot.py:1066: MatplotlibDeprecationWarning: 
The set_smart_bounds function was deprecated in Matplotlib 3.2 and will be removed two minor releases later.
  self.ax[i].spines['bottom'].set_smart_bounds(False)
%
時刻: 18:00 ラベル: , , , ,

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