Matt J
Posts:
4,996
Registered:
11/28/09


Re: matrix multiplication with zero dimensions
Posted:
Jan 7, 2013 6:26 AM


"James Tursa" wrote in message <kcdu10$8bi$1@newscl01ah.mathworks.com>... > "Roger Stafford" wrote in message <kcdmmk$ekv$1@newscl01ah.mathworks.com>... > > "Matt J" wrote in message <kcdl09$975$1@newscl01ah.mathworks.com>... > > > But... I still think these things should be documented somewhere. They don't satisfy the basic definitions of matrix multiplication, PROD, or SUM. They're just extrapolations of them. > >        > > I agree with you there. It should have been explicitly documented somewhere. > > > > Roger Stafford > > Quoting from the doc for mtimes: > > "Note If A is an mby0 empty matrix and B is a 0byn empty matrix, where m and n are positive integers, A*B is an mbyn matrix of all zeros."
That's good. But I meant also that sum([])=0 and prod([])=1 should be documented somewhere as well. Maybe I just haven't found it yet, though.

