spy2.m

With this you can easier se the element locations of matrices.

This is another "spy"-function which, instead of MATLAB's spy function draws each element in a matrix as a square, which makes it much easier to see where each element in the matrix is located.
The syntax is: SPY(M[,COLOR]).

SPY2(A) where A is a matrix, will plot
the matrix with color codes.
Elements containing NaN or Inf will be
counted as non-zero but will be
displayed as zero elements.

SPY2(A,COLOR) will plot zero elements
with white color and nonzero elements
with black color.
Elements containing NaN or Inf will be
counted as non-zero and will also be
displayed as non-zero elements.

The displayed matrix will have sides
proportional to the number of elements
in each row/column.
If the matrix contains complex numbers,
only the real part will be displayed.

NB! For matrix sizes > 400 x 400, it will be hard to see the elements if you don't increase the figure size.

more programs/toolboxes can be found at:
http://www.etek.chalmers.se/~e8rasmus/eng/matlab_programs.html