Aaaargh!  I'm going crazy here.  If anyone can help I will be massively grateful!

My problem is quite simple:  I have a long list of data, in the form: f1:=[some matrix] f2:=[another matrix]...etc.

The data has been read in from a different program.  I am trying to write a program to go through each matrix one by one and perform some operations on it.  Usually to do this I take some dummy variable, say i or j, and write: