Re: column * row ??
- To: mathgroup at smc.vnet.net
- Subject: [mg28819] Re: column * row ??
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Tue, 15 May 2001 00:58:54 -0400 (EDT)
- References: <9dlcc6$o2p@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
John,
We need to make the lists into matrice -- column and row matrices:
{{a1},{a2},{a3}}.{{b1,b2}}
{{a1 b1,a1 b2},{a2 b1,a2 b2},{a3 b1,a3 b2}}
--
Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565
"J.R. Chaffer" <jrchaff at mcn.net> wrote in message
news:9dlcc6$o2p at smc.vnet.net...
> Hi there,
>
> Can someone tell me a way to mimic the building of
> an N x N matrix by multiplying a column vector
> on left times a row vector on right ? (both vectors
> of length N) - I mean in Mathematica, of course.
>
> i.e, want the result,
>
> (colvec){a1,a2, .. aN} * (rowvec){b1,b2,..bN} =
>
> result is matrix:
>
> {{a1*b1 a1*b2 ..... a1*bN},
> {a2*b1 a2*b2 ..... a2*bN},
> ... ... ... ,
> {aN*b1 aN*b2 ..... aN*bN}}
>
>
> When I try this in Mathematica all I can figure out
> how to produce is the standard dot-product. If I
> try the 'transposed' lists/matrices, I get an error,
> even tho the product is defined by basic rules of
> matrix multiplication.
>
> Thanks,
>
> John Chaffer
>