How to perform mathematical operation between all elements of arrays with unequal numbers

I have two arrays A & B, being a nXm and a pXq array, repsctively. I want to take A(i,j) and multiply it in or subtract it from all elements of B. Then I will take the next element of A and so on. is it possible to do without using a loop on all elements?

Answer 1

[John D'Errico]

A = rand(2,3);
B = rand(4,5);

C = A + reshape(B,[1,1,size(B)]); % Addition
C = A - reshape(B,[1,1,size(B)]); % subtraction
size(C)
ans =
     2     3     4     5

D = A .* reshape(B,[1,1,size(B)]); % multiplication
D = A ./ reshape(B,[1,1,size(B)]); % division
size(D)
ans =
     2     3     4     5

This is possible as long as you have MATLAB release 2016b or later. Earlier releases will need to use bsxfun instead.

help bsxfun

Note that you use .* and ./ for elementwise multiplication/division, not the * or / operators.

[Saeid]

Thanks, John!

Answer 2

[Matt J]

Here is how you would do the subtraction

A-reshape(B,1,1,p,q)  %result is nXmXpxq

but it will work equally well with any other operation that supports implicit expansion.