frustrated wrote...
For Excel 2000 I have found a freeware add-in that allows manipulation of
matrices with complex values, i.e. matrix multiplication, matrix inversion
etc... Is there such an add-in, free or not, for Excel 2003? The add-in I
have for Excel 2000 is not compatible with Excel 2003.

Meaning you've tried running this add-in under Excel 2003 and it
doesn't work? Or are you just assuming it won't work under Excel 2003?