You mean something like this:
% Make some sample data.
m=rand(1, 10)
% See where it exceeds 0.5.
biggerThanPoint5 = m > 0.5
% Make some other array that we want to act upon.
out = 11 * ones(1,10)
% Set out = 99 where m>0.5
out(biggerThanPoint5) = 99
Results in command window:
m =
0.4898 0.4456 0.6463 0.7094 0.7547 0.2760 0.6797 0.6551 0.1626 0.1190
biggerThanPoint5 =
0 0 1 1 1 0 1 1 0 0
out =
11 11 11 11 11 11 11 11 11 11
out =
11 11 99 99 99 11 99 99 11 11
