Avoid loops in Matlab

Following examples demonstrate how one can avoid for loops in MATLAB to speed up execution :

1. Vector assignment
   
   x = rand(1,100);
   %In spite of :
   for k=1:100
   y(k) = sin(x(k));
   end
   % We can use :
   y(:) = sin(x(:));
   
   
   
2. Subtracting a vector from each row/column of a matrix
   
   a = [1 2 3]
   b = magic(3);
   c = repmat(a,3,1) - b;
   
   
3. Use logical indexing to operate on a part of a matrix. Use "find" command wherever possible.
   
   a = 200:-10:50;
   % replace the value 120 by 0
   a(find(a == 120)) = 0;
   a =   200   190   180   170   160   150   140   130     0   110   100    90    80    70    60    50
   
   Another example :
   
   % [idx1, idx2] = find(angle < 0);
   % idx = [idx2 idx2];
   % for j = 1:length(idx)
   %     angle(idx(j,1),idx(j,2))=360+angle(idx(j,1),idx(j,2));
   % end
   can be replaced by following code :
   
   angle(angle<0) = angle(angle<0)+360;
   
   
   
4. Useful commands for matrices and vectors :
   
   sum, norm, diff, abs, max, min, sort
   
   
   

   Useful link in this direction

   http://www.ee.columbia.edu/~marios/matlab/matlab_tricks.html