matrix multiplication in matlab

XYZ=[0.5141 0.3239 0.1604;0.2651 0.6702 0.0641;0.0241 0.1228 0.8444];
  for i=1:768
      for h=1:768
         nf=mR(i,h);
         fd=mG(i,h);
         gs=mB(i,h);
       bv=[nf fd gs];
       hd=bv';
       disp(hd);
        mmul=double(hd).*XYZ;
       disp(mmul);
      end
  end

Error using .* Matrix dimensions must agree.

Error in Untitled6 (line 22) mmul=double(hd).*XYZ;

Answer 1

[Jan]

All we see is the failing code, and we have to guess its intention. Better explain this to get the solution you want.

double(hd) .* XYZ
[3 x 1]    .* [3 x 3]

Do you want the result to be [3 x 3]? This works in Matlab >= 2016b with automatic expanding. With older versions, the elementwise multiplication demands for two arguments of the same size. Then:

mmul = bsxfun(@times, double(hd), XYZ);

or

mmul = double(hd(:, [1,1,1]) .* XYZ;

But perhaps you want a matrix multiplication?

mmul = double(bv) * XYZ;

[Rik]

Also: you should convert numbers to strings before using disp. You can use fprintf, a combination of sprintf and disp, or a combination of num2str and disp. I strongly advise the first.

[Jan]

@Rik: disp works well with numbers and arrays:

x = rand(2)
disp(x)