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 infoAdvertise with us Next Article numpy matrix operations | randn() function J jana_sayantan Follow Improve Article Tags : Python Python-numpy Python numpy-Matrix Function Practice Tags : python Similar Reads numpy matrix operations | rand() function numpy.matlib.rand() is another function for doing matrix operations in numpy. It returns a matrix of random values from a uniform distribution over [0, 1) with given shape. Syntax : numpy.matlib.rand(*args) Parameters : *args : [Arguments] Shape of the output matrix. If given as N integers, each int 2 min read numpy matrix operations | repmat() function numpy.matlib.repmat() is another function for doing matrix operations in numpy. It returns Repeat a 0-D, 1-D or 2-D array or matrix M x N times. Syntax : numpy.matlib.repmat(a, m, n) Parameters : a : [array_like] The input array or matrix which to be repeated. m, n : [int] The number of times a is r 2 min read numpy matrix operations | zeros() function numpy.matlib.zeros() is another function for doing matrix operations in numpy. It returns a matrix of given shape and type, filled with zeros. Syntax : numpy.matlib.zeros(shape, dtype=None, order='C') Parameters : shape : [int, int] Number of rows and columns in the output matrix.If shape has length 2 min read numpy matrix operations | eye() function numpy.matlib.eye() is another function for doing matrix operations in numpy. It returns a matrix with ones on the diagonal and zeros elsewhere. Syntax : numpy.matlib.eye(n, M=None, k=0, dtype='float', order='C') Parameters : n : [int] Number of rows in the output matrix. M : [int, optional] Number o 2 min read numpy matrix operations | ones() function numpy.matlib.ones() is another function for doing matrix operations in numpy. It returns a matrix of given shape and type, filled with ones. Syntax : numpy.matlib.ones(shape, dtype=None, order='C') Parameters : shape : [int, int] Number of rows and columns in the output matrix.If shape has length on 2 min read Like