Python | Numpy matrix.sum() Last Updated : 17 Nov, 2025 Comments Improve Suggest changes 2 Likes Like Report matrix.sum() is a NumPy function used to calculate the sum of all elements in a matrix. It can also compute row-wise and column-wise sums using the axis parameter. This method works only with NumPy matrix objects, not arrays.Example:Input: [[1, 2], [3, 4]]Output: 10Syntaxmatrix.sum(axis=None)Parameter: axis (Optional) -None: sum of all elements0: column-wise sum1: row-wise sumExamplesExample 1: This example creates a 2×2 matrix using np.matrix and computes the sum of all its elements using matrix.sum(). Python import numpy as np m = np.matrix([[4, 1], [12, 3]]) out = m.sum() print(out) Output20 Explanation: m.sum() adds all elements (4 + 1 + 12 + 3 = 20).Example 2: This example calculates the sum of each row separately by setting axis=1. Python import numpy as np m = np.matrix([[4, 1, 9], [12, 3, 1], [4, 5, 6]]) out = m.sum(axis=1) print(out) Output[[14] [16] [15]] Explanation: m.sum(axis=1) sums each row individually.Example 3: This example finds the sum of each column in a 3×3 matrix using axis=0. Python import numpy as np m = np.matrix([[2, 4, 6], [1, 3, 5], [7, 8, 9]]) out = m.sum(axis=0) print(out) Output[[10 15 20]] Explanation: m.sum(axis=0) sums column-wise (2+1+7), (4+3+8), (6+5+9) Create Quiz Comment J jitender_1998 Follow 2 Improve J jitender_1998 Follow 2 Improve Article Tags : Python Python-numpy Python numpy-Matrix Function Explore Python FundamentalsPython Introduction 2 min read Input and Output in Python 4 min read Python Variables 4 min read Python Operators 4 min read Python Keywords 2 min read Python Data Types 8 min read Conditional Statements in Python 3 min read Loops in Python - For, While and Nested Loops 5 min read Python Functions 5 min read Recursion in Python 4 min read Python Lambda Functions 5 min read Python Data StructuresPython String 5 min read Python Lists 4 min read Python Tuples 4 min read Python Dictionary 3 min read Python Sets 6 min read Python Arrays 7 min read List Comprehension in Python 4 min read Advanced PythonPython OOP Concepts 11 min read Python Exception Handling 5 min read File Handling in Python 4 min read Python Database Tutorial 4 min read Python MongoDB Tutorial 3 min read Python MySQL 9 min read Python Packages 10 min read Python Modules 3 min read Python DSA Libraries 15 min read List of Python GUI Library and Packages 3 min read Data Science with PythonNumPy Tutorial - Python Library 3 min read Pandas Tutorial 4 min read Matplotlib Tutorial 5 min read Python Seaborn Tutorial 3 min read StatsModel Library - Tutorial 3 min read Learning Model Building in Scikit-learn 6 min read TensorFlow Tutorial 2 min read PyTorch Tutorial 6 min read Web Development with PythonFlask Tutorial 8 min read Django Tutorial | Learn Django Framework 7 min read Django ORM - Inserting, Updating & Deleting Data 4 min read Templating With Jinja2 in Flask 6 min read Django Templates 5 min read Build a REST API using Flask - Python 3 min read Building a Simple API with Django REST Framework 3 min read Python PracticePython Quiz 1 min read Python Coding Practice 1 min read Python Interview Questions and Answers 15+ min read Like