Help comparing two matrices

so I need to compare two matrices but I need to set the values the final compared matrice will have... so for example if one value is higher than the other it should display 1; if it is lower -1 and finally if it is equal 0. I have been messing with this but cant figure it out I think I need a way to go over the two matrices comparing the two elements and but then how do I set those elements back into a matrice....? why is it so complicated!!!

well i need a function... sorry and thanks for the responses

[Image Analyst]

You already asked this and got answers from Roger and Azzi, and you accepted one: here is your duplicate question, so why are you asking again??? For what it's worth, I like Roger's and Matt's solution of using sign() best.

Answer 1

[Amy]

You can use logical indexing for that. If m1 is the first matrix and m2 is the second and C is the comparison, I think you want something like:

C = zeros(size(m1));
C(m1>m2) = 1; % fill in 1 wherever m1 is greater than m2
C(m2>m1) = -1; % fill in -1 wherever m2 is greater

This assumes there are no nans. If that's the case you might initialize C to NaNs and then add a line for the case of m1==m2.

[Antonio]

but how do you integrate that in a function?

function [C]=comparaMatrices(m1,m2)
.....
.....

I cant get it working...sorry im a noob

Answer 2

[Matt J]

   C=sign(A-B),