Use While loop for a matrix

I have a variable A with 517X519 size and variable B with 517X519. I will like to use a while loop. for example, I will like to do: while A > B. so that A goes through all the cells in B (268323) and check if condition are met. I get this error message

Warning: Rank deficient, rank = 1, tol =  3.035597e-12. 
Matrix dimensions must agree.

Can some please assist.

[KL]

...goes through all the cells in B (268323)...

Do you want to compare every element of A with all the elements of B?

[Ayodele Ogunkoya]

Yes i want to compare the every element of A with all element of B

[Walter Roberson]

It sounds as if your code uses the / operator on matrices at some point. Either you are expecting only scalars at that point but have matrices (or vectors) instead, or else you know you are operating on matrices but should have used ./ instead of /