# how to create logical matrix directly in matlab

I have so far been using

a = logical(zeros(10,10))

to create logical matrix.

Is there a way to create it directly?

## Answers

Use false directly:

a = false(10,10);

In Matlab, there are a few 'constants' that are actually matrix-generating commands. They are:

true(10); true(n,m,k,..); % for an all-true 10-by-10 or n-by-m-by-k-by-...matrix false(10); false(n,m,k,..); % for an all-false 10-by-10 or n-by-m-by-k-by-...matrix inf(10); inf(n,m,k,..); % for an all-inf 10-by-10 or n-by-m-by-k-by-...matrix nan(10); nan(n,m,k,..); % for an all-nan 10-by-10 or n-by-m-by-k-by-...matrix

The 'constant' forms are basically just aliases:

a = inf; % alias for a = inf(1); b = true; % alias for b = true(1);

etc. Also, here are some more things that cannot be repeated enough:

rand(10); rand(n,m,k,..); % for an all-random 10-by-10 or n-by-m-by-k-by-...matrix zeros(10); zeros(n,m,k,..); % for an all-zero 10-by-10 or n-by-m-by-k-by-...matrix zeros(n,m,k,...,'uint8'); % for an all-zero n-by-m-by-k-by-...matrix of type uint8 ones(10); zeros(n,m,k,..); % for an all-one 10-by-10 or n-by-m-by-k-by-...matrix ones(n,m,k,...,'uint8'); % for an all-one n-by-m-by-k-by-...matrix of type uint8 eye(10); eye(n,m,'uint8'); % for an identity matrix of type uint8 of 10-by-10 or n-by-m

Matlab's logical data type does not appear to have a constructor other than the logical function itself. That being said, you can effectively typecast a double array as a logical array very easily, where all nonzero values become logic 1 and all zeros logic 0:

A = [1 0 2; -1 0 0; 0 1.53 -100.00] B = logical(A) B = 1 0 1 1 0 0 0 1 1

You can obviously condense this assignment to one line if you'd like, so it becomes nearly as simple as assigning any other data type.