The short-circuiting behavior of && is occasionally useful for performance optimization. If you use more intensive conditions, you'll likely see some effect. Here's an example:
T = 100;
q = zeros(1000,1);
tic
for i = 1:T
if (all(q == 1) && (numel(q) > 100))
end
end
toc;
tic;
for i = 1:T
if (all(q == 1) & (numel(q) > 100))
end
end
toc;
It's sometimes valuable to optimize code by structuring the order of conditions according to likelihood and expense. For example, a quick check that often returns false should be evaluated first in a && expression.
Another aspect of short-circuiting that makes it valuable is that it allows you to write defensive code to check for the presence of a valid variable to test. For example, let's assume you have a variable v that is intialized to empty but may be set to an object at some point. You can use short-circuiting to write conditional checks like:
if ~isempty(v) && v.DoSomethingFlag
