A more short code forgenerating a random matrix A of (1,-1);

A more short code for generating a random matrix A of (1,-1),no loop

Description

A more short code for generating a random matrix A of (1,-1),no loop

• MATLAB release: MATLAB 7.10 (2010a)

[James Tursa]

This submission has the following problems:
1) It uses the relatively expensive power operator and bsxfun to generate the +1 and -1 values.
3) No H1 line.
4) No help.
5) A much faster (more than 3x faster) one-liner equivalent to this submission is as follows: floor(rand(n)*2)*2-1
6) There is no provision for multi-dimensional sizes. Only 2D sizes are supported.

James Tursa

[James Tursa]

Typo. The one-liner equivalent is: floor(rand(m,n)*2)*2-1

[Binbin Qi]

thank you,I think the following is efficient
A=round(rand(m,n))*2-1;
A=floor(rand(m,n)*2)*2-1;
A=fix(rand(m,n)*2)*2-1;
A=randi([0,1],m,n)*2-1;

[Matt Fig]

A general, ND version could look like:

function A = randmatrix(varargin)
A = floor(rand(varargin{:})*2)*2-1;

The 2D limitation, in addition to the need for usable help, a more descriptive name (something like RANDSIGNONES at least describes more closely what the code produces), and an H1 line prevent the file from being that useful as it now stands.