20060315-Quick tip: Use the functions true and false

原文：http://blogs.mathworks.com/steve/2006/03/15/quick-tip-use-the-functions-true-and-false/

I saw some code recently that looked something like this:

B = zeros(size(A));
B = logical(B);

The intent of the code was to initialize an all-zero binary image with the same size as
A. Note, however, that the output of the zeros function in the first line is a double-precision array, which requires
eight bytes per element. Logical arrays in MATLAB, on the other hand, use
only one byte per element. It's quicker and more memory efficient to initialize B using the
false function.

The functions true and
false are most often seen without input arguments, in which case they return a scalar logical 1 or a scalar logical 0, respectively. But they also support an optional size input. So the following code works just as well for initializing the
binary image:

B = false(size(A));