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Topic: matrix multiplication with zero dimensions
Replies: 11   Last Post: Jan 7, 2013 10:20 AM

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Matt J

Posts: 4,996
Registered: 11/28/09
Re: matrix multiplication with zero dimensions
Posted: Jan 7, 2013 6:26 AM
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"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 m-by-0 empty matrix and B is a 0-by-n empty matrix, where m and n are positive integers, A*B is an m-by-n 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.



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