Question

I have a large vector containing integers (length: 230 400, int8) which I rearrange into a 3-dimensional matrix (rows: 240, cols: 320, depth: 3). When this has been done the new matrix contains doubles instead of ints (according to Matlab Workspace).

The whole operation takes 0.3 seconds, which is to long for my purposes.

Is Matlab converting the ints in the array to doubles before putting them in the matrix?
Can this be avoided to speed it up?

Some code:

   tic;
   A=zeros(240,320,3);
   %A is matrix, B is vector.

   for i=1:240
       for j=1:320
           A(i,j,:)=B(1+(j-1)*3+(i-1)*320*3:3+(j-1)*3+(i-1)*320*3);
       end
   end

   toc;

Thanks!

Answer 1

Try initializing your matrix with

A=zeros(240, 320, 3, 'int8')