Change elements of matrix based on condition

Question

Suppose I have Matrix A:

A =

 1     2     3
 4     5     6   

For every element x<2, add 10,
for every element x

Answer 1

You don't need an IF you need logical indexing:

    IndexOfLessThan2 = A < 2;
    IndexOfGreaterThan5 = A > 5;
    IndexBtw2and5 = ~(IndexOfLessThan2 | IndexOfGreaterThan5);

    A = A + IndexOfLessThan2*10 + IndexOfGreaterThan5*20 + IndexBtw2and5*30;