Lots of folks continue to look for this capability as an existing
package. I suppose the existing tensor algebra/differential forms/
Grassmann algebra packages might be coerced by the knowledgeable, but
for those of us just wanting plain old vectors and matrices, check
out:
http://www.ms.hum.titech.ac.jp/sumopack/sumopack.zip
by Shin-ichi Mayekawa
which I found via
http://bm.hus.osaka-u.ac.jp/~taco/lecture/2009/mayekawa/IMPS2006_1.ppt
Comments/feedback to the group would be helpful!