newRPL - build 1255 released! [updated to 1299]

[The Shadow]

I'm not clear on why you need a symbol for the identity matrix for those particular rules? Matrices can be multiplied by a scalar just fine. EDIT: In fact, in standard linear algebra you *can't* add the identity matrix to a scalar.

You might well need the identity matrix in other contexts, though.

EDIT: Where problems do arise is in the rule eliminating an added zero. For matrices, that would have to be the zero matrix. But since you're getting rid of it anyway, maybe it's not too much of a problem?

I wonder if we need a separate MATRIXSIMPLIFY command?