Here are more concise ways of deleting rows and columns without using
the built-in submatrix function:
removerow(m,r):=part(m,allbut(r))$
removecol(m,c):=transpose(removerow(transpose(m),c))$
Removerow is about as efficient as submatrix. Removecol is slower,
because it has to make two complete copies of the matrix. Both are
faster than the genmatrix approach, since part is native. The addrow
approach is inefficient because it makes many new matrices. The addcol
approach is even more inefficient. I tried to measure speeds of
compiled code, but there was a bug in Translate (887152 -- fix supplied)
and a bug in Genmatrix/lambda (887174 -- yuck).
-s