Richard,
This has to be wrapped up in a program, right?
Whoops, you are right; only an eclass program can do an ereturn repost. I
thought -eret2- might let you do it interactively but it gives me a syntax
error when I try to change e(b). Assuming this is something you want to do
more than once though, perhaps this would be the way to go: (a) write a
program whose sole purpose in life is to issue the ereturn repost command
(b) make your changes interactively and then call the program with the name
of your altered matrix. Example: