numpy matrix operations | randn() function Last Updated : 21 Feb, 2019 Comments Improve Suggest changes Like Article Like Report numpy.matlib.randn() is another function for doing matrix operations in numpy. It returns a matrix of random values from a univariate “normal” (Gaussian) distribution of mean 0 and variance 1. Syntax : numpy.matlib.randn(*args) Parameters : *args : [Arguments] Shape of the output matrix. If given as N integers, each integer specifies the size of one dimension. If given as a tuple, this tuple gives the complete shape.If there are more than one argument and the first argument is a tuple then other arguments are ignored. Return : The matrix of random values drawn from the standard normal distribution. Code #1 : Python3 # Python program explaining # numpy.matlib.randn() function # importing matrix library from numpy import numpy as geek import numpy.matlib # desired 3 x 4 random output matrix out_mat = geek.matlib.randn((3, 4)) print ("Output matrix : ", out_mat) Output : Output matrix : [[ 0.78620217 0.41624612 -0.28417131 0.1071018 ] [ 0.77645105 0.30858858 -1.98901344 1.25977209] [ 0.26279443 -0.41026178 -0.60834494 2.82552737]] Code #2 : Python3 # Python program explaining # numpy.matlib.randn() function # importing numpy and matrix library import numpy as geek import numpy.matlib # desired 1 x 5 random output matrix out_mat = geek.matlib.randn(5) print ("Output matrix : ", out_mat) Output : Output matrix : [[ 0.34973625 0.28159132 0.72581405 -1.17511692 1.96773952]] Code #3 : Python3 # Python program explaining # numpy.matlib.randn() function # importing numpy and matrix library import numpy as geek import numpy.matlib # more than one argument given out_mat = geek.matlib.randn((5, 3), 4) print ("Output matrix : ", out_mat) Output : Output matrix : [[ 0.56784957 0.82980325 1.16683558] [-1.53444326 -0.27743273 0.65819067] [ 0.99654573 -1.20399432 -0.25603147] [ 1.74931585 0.58413453 1.67820029] [-1.25643231 0.21610229 0.21694595]] Note: For random samples from N(\mu, \sigma^2) we can use sigma * geek.matlib.randn(...) + mu . For example, making a 3 x 3 matrix in which samples are taken from N(3, 4): Code #4 : Python3 # Python program explaining # numpy.matlib.randn() function # importing numpy and matrix library import numpy as geek import numpy.matlib # So, here mu = 3, sigma = 2 out_mat = 2 * geek.matlib.randn((3, 3)) + 3 print ("Output matrix : ", out_mat) Output : Output matrix : [[ 4.04967121 0.26982021 2.3503067 ] [ 5.57757131 2.40051874 -0.84588539] [ 7.43715651 3.84004412 1.40514615]] Comment More info J jana_sayantan Follow Improve Article Tags : Python Python-numpy Python numpy-Matrix Function Explore Python FundamentalsPython Introduction 3 min read Input and Output in Python 4 min read Python Variables 5 min read Python Operators 5 min read Python Keywords 2 min read Python Data Types 7 min read Conditional Statements in Python 3 min read Loops in Python - For, While and Nested Loops 6 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 2 min read Python MySQL 9 min read Python Packages 12 min read Python Modules 7 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 6 min read Matplotlib Tutorial 5 min read Python Seaborn Tutorial 15+ min read StatsModel Library- Tutorial 4 min read Learning Model Building in Scikit-learn 8 min read TensorFlow Tutorial 2 min read PyTorch Tutorial 7 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 7 min read Python | Build a REST API using Flask 3 min read How to Create a basic API using Django Rest Framework ? 4 min read Python PracticePython Quiz 3 min read Python Coding Practice 1 min read Python Interview Questions and Answers 15+ min read Like