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


Re: matrix multiplication with zero dimensions
Posted:
Jan 6, 2013 7:32 PM


"Bruno Luong" <b.luong@fogale.findmycountry> wrote in message <kcd1lg$6u4$1@newscl01ah.mathworks.com>... > "Matt J" wrote in message <kcd0g0$34t$1@newscl01ah.mathworks.com>... > > > Just like sum([]), prod([]), this result is no exception so to be documented separately. ==============
I can see the rational behind sum([])=0and prod([])=1. It's so that
sum([A,[]],2)=sum(A,2)+sum([]) prod([A,[]],2)=prod(A,2)*prod([])
I do not see the rationale behind the originally posted relationship, though. Taking a slightly different example, I can see perhaps that
ones(3,0)*ones(0,3)
should end up being 3x3 because of the outer dimensions, but why should it end up containing zeros.

