How exactly should element B(r, c) be computed from the elements of x and y?
Rather than using random data, let x = 1:5 and y = 6:11. Show us the B matrix that those two vectors should generate and exactly the rule you follow in generating say B(2, 4).
If the elements in B aren't supposed to be related to the elements in x and y, and you just want to use x and y to indicate the size of the random B matrix to be created:
x = 1:5;
y = 6:11;
B = rand(numel(x), numel(y))
