# NumPy Matrix Vector Multiplication

Muhammad Maisam Abbas Jan 30, 2023 May 24, 2021 NumPy NumPy Matrix

This tutorial will introduce the methods to multiply two matrices in NumPy.

## NumPy Matrix Vector Multiplication With the `numpy.matmul()` Method

To calculate the product of two matrices, the column number of the first matrix must be equal to the row number of the second matrix. The `numpy.matmul()` method is used to calculate the product of two matrices. The `numpy.matmul()` method takes the matrices as input parameters and returns the product in the form of another matrix. See the following code example.

``````import numpy as np

m1 = np.array([[1,2,3],[4,5,6],[7,8,9]])
m2 = np.array([[9,8,7,6],[5,4,3,3],[2,1,2,0]])

m3 = np.matmul(m1,m2)
print(m3)
``````

Output:

``````[[ 25  19  19  12]
[ 73  58  55  39]
[121  97  91  66]]
``````

We first created the matrices in the form of 2D arrays with the `np.array()` method. We then calculated the product of both matrices with the `np.matmul(m1,m2)` method and stored the result inside the `m3` matrix.

## NumPy Matrix Vector Multiplication With the `numpy.dot()` Method

The `numpy.dot()` method calculates the dot product of two arrays. It can also be used on 2D arrays to find the matrix product of those arrays. The `numpy.dot()` method takes two matrices as input parameters and returns the product in the form of another matrix. See the following code example.

``````import numpy as np

m1 = np.array([[1,2,3],[4,5,6],[7,8,9]])
m2 = np.array([[9,8,7,6],[5,4,3,3],[2,1,2,0]])

m3 = np.dot(m1,m2)
print(m3)
``````

Output:

``````[[ 25  19  19  12]
[ 73  58  55  39]
[121  97  91  66]]
``````

We first created the matrices in the form of 2D arrays with the `np.array()` method. We then calculated the product of both matrices with the `np.dot(m1,m2)` method and stored the result inside the `m3` matrix.

Maisam is a highly skilled and motivated Data Scientist. He has over 4 years of experience with Python programming language. He loves solving complex problems and sharing his results on the internet.