>>> from numpy import pi

>>> np.linspace(0, 2, 9)

array([0.  , 0.25, 0.5 , 0.75, 1.  , 1.25, 1.5 , 1.75, 2.  ])

>>> x = np.linspace(0, 2*pi, 100)

>>> y = np.sin(x)

>>> import matplotlib.pyplot as plt

>>> plt.plot(x, y, 'o')

[<matplotlib.lines.Line2D object at 0x0000021025D65BA8>]

>>> plt.show()

>>> import numpy as np

>>> import matplotlib.pyplot as plt

>>> from numpy import pi

>>> x = np.linspace(0, 2*pi, 100)

>>> y1 = np.sin(x)

>>> y2 = np.cos(x)

>>> # sin

>>> plt.plot(x, y1, 'g')

[<matplotlib.lines.Line2D object at 0x000002C068E4C940>]

>>> # cos

>>> plt.plot(x, y2, 'r')

[<matplotlib.lines.Line2D object at 0x000002C068E4CA90>]

>>> # x = 0

>>> y = np.linspace(-1, 1, 100)

>>> plt.plot(x*0, y, 'b')

[<matplotlib.lines.Line2D object at 0x000002C068E4CCF8>]

>>> # x = 2*pi

>>> plt.plot(x*0 + 2*pi, y, 'b')

[<matplotlib.lines.Line2D object at 0x000002C068E4CD68>]

>>> # y = 1

>>> plt.plot(x, y*0 + 1, 'b')

[<matplotlib.lines.Line2D object at 0x000002C05EEB4C50>]

>>> # y = -1

>>> plt.plot(x, y*0 - 1, 'b')

[<matplotlib.lines.Line2D object at 0x000002C068E61E10>]

>>> plt.show()

>>> A = np.array([[1,1],

		  [0,1]])

>>> B = np.array([[2,0],

		  [3,4]])

>>> A * B        # 点乘，对应点的乘积

array([[2, 0],

       [0, 4]])

>>> A @ B        # 矩阵乘法

array([[5, 4],

       [3, 4]])

>>> A.dot(B)        # 矩阵乘法

array([[5, 4],

       [3, 4]])

>>> A * 2        # 乘以数字

array([[2, 2],

       [0, 2]])

>>> A / 2        # 除以数字

array([[0.5, 0.5],

       [0. , 0.5]])

>>> A + B        # 矩阵加法

array([[3, 1],

       [3, 5]])

>>> A - B        # 矩阵减法

array([[-1,  1],

       [-3, -3]])

>>> B ** 2        # 对矩阵每个元素取平方

array([[ 4,  0],

       [ 9, 16]], dtype=int32)