Test every element in matrix

I have an M x N matrix, where I want to test whether each element is greater than some constant a, and if it is, perform some arithmetic to it. The only way I can think of doing this is using 2 For loops nested to select each element and an If statement to perform checking. Is this the best I can do?

Answer 1

[Tigersnooze]

You can say something like this, instead of using a loop (assuming the matrix is called A):

A(A > a) = A(A > a) + arithmetic.

"Vectorizing" like this won't have significant speed advantages with smaller matrices, but when the matrix gets bigger you'll see huge time savings. Just a heads up for the future.

[Leor Greenberger]

Thank you! this is perfect!

[Leor Greenberger]

How would I go about doing this for a matrix A where I want to check whether each element == any value in some vector b.

A(A == b) doesn't work (didn't think it would)

[Sean de Wolski]

Leor, look at ismember:

doc ismember

[Leor Greenberger]

Thank you, sir!