Matrix Multiplication in NumPy
Let us see how to compute matrix multiplication with NumPy. We will be using the numpy.dot() method to find the product of 2 matrices.
For example, for two matrices A and B.
A = [[1, 2], [2, 3]]
B = [[4, 5], [6, 7]]
So, A.B = [[1*4 + 2*6, 2*4 + 3*6], [1*5 + 2*7, 2*5 + 3*7]
So the computed answer will be: [[16, 26], [19, 31]]
In Python numpy.dot() method is used to calculate the dot product between two arrays.
Example 1 : Matrix multiplication of 2 square matrices.
import numpy as np
p = [[ 1 , 2 ], [ 2 , 3 ]]
q = [[ 4 , 5 ], [ 6 , 7 ]]
print ( "Matrix p :" )
print (p)
print ( "Matrix q :" )
print (q)
result = np.dot(p, q)
print ( "The matrix multiplication is :" )
print (result)
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Output :
Matrix p :
[[1, 2], [2, 3]]
Matrix q :
[[4, 5], [6, 7]]
The matrix multiplication is :
[[16 19]
[26 31]]
Example 2 : Matrix multiplication of 2 rectangular matrices.
import numpy as np
p = [[ 1 , 2 ], [ 2 , 3 ], [ 4 , 5 ]]
q = [[ 4 , 5 , 1 ], [ 6 , 7 , 2 ]]
print ( "Matrix p :" )
print (p)
print ( "Matrix q :" )
print (q)
result = np.dot(p, q)
print ( "The matrix multiplication is :" )
print (result)
|
Output :
Matrix p :
[[1, 2], [2, 3], [4, 5]]
Matrix q :
[[4, 5, 1], [6, 7, 2]]
The matrix multiplication is :
[[16 19 5]
[26 31 8]
[46 55 14]]
Last Updated :
02 Sep, 2020
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