使用 NumPy
计算矩阵和向量的内积、外积和叉积
原文:https://www . geeksforgeeks . org/compute-in-external-and-cross-乘积矩阵和向量-使用-numpy/
我们来讨论一下如何用 Python 中的 NumPy 来求矩阵和向量的内积、外积和叉积。
向量和矩阵的内积
求向量和矩阵的内积，可以用 NumPy 的 【内积() 方法。 语法:
numpy.inner(arr1, arr2)
代码:
Python 3
# Python Program illustrating
# numpy.inner() method
import numpy as np
# Vectors
a = np.array([2, 6])
b = np.array([3, 10])
print("Vectors :")
print("a = ", a)
print("\nb = ", b)
# Inner Product of Vectors
print("\nInner product of vectors a and b =")
print(np.inner(a, b))
print("---------------------------------------")
# Matrices
x = np.array([[2, 3, 4], [3, 2, 9]])
y = np.array([[1, 5, 0], [5, 10, 3]])
print("\nMatrices :")
print("x =", x)
print("\ny =", y)
# Inner product of matrices
print("\nInner product of matrices x and y =")
print(np.inner(x, y))
输出:
向量和矩阵的外积
向量和矩阵的外积可以用 NumPy 的 【外() 方法求出。 语法:
numpy.outer(a, b, out = None)
代码:
Python 3
# Python Program illustrating
# numpy.outer() method
import numpy as np
# Vectors
a = np.array([2, 6])
b = np.array([3, 10])
print("Vectors :")
print("a = ", a)
print("\nb = ", b)
# Outer product of vectors
print("\nOuter product of vectors a and b =")
print(np.outer(a, b))
print("------------------------------------")
# Matrices
x = np.array([[3, 6, 4], [9, 4, 6]])
y = np.array([[1, 15, 7], [3, 10, 8]])
print("\nMatrices :")
print("x =", x)
print("\ny =", y)
# Outer product of matrices
print("\nOuter product of matrices x and y =")
print(np.outer(x, y))
输出:
向量和矩阵的叉积
为了找到向量和矩阵的叉积，我们可以使用 NumPy 的 cross() 方法。
语法:
numpy.cross(a, b)
代码:
Python 3
# Python Program illustrating
# numpy.cross() method
import numpy as np
# Vectors
a = np.array([3, 6])
b = np.array([9, 10])
print("Vectors :")
print("a = ", a)
print("\nb = ", b)
# Cross product of vectors
print("\nCross product of vectors a and b =")
print(np.cross(a, b))
print("------------------------------------")
# Matrices
x = np.array([[2, 6, 9], [2, 7, 3]])
y = np.array([[7, 5, 6], [3, 12, 3]])
print("\nMatrices :")
print("x =", x)
print("\ny =", y)
# Cross product of matrices
print("\nCross product of matrices x and y =")
print(np.cross(x, y))
输出:
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