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MathGroup Archive 2006

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Re: Can't multiply non-square matrices.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg64599] Re: [mg64549] Can't multiply non-square matrices.
  • From: "Yasvir A. Tesiram" <tesiramy at omrf.ouhsc.edu>
  • Date: Thu, 23 Feb 2006 00:35:33 -0500 (EST)
  • References: <200602221058.FAA23442@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

G'day,
Is this what you were after?

x = {{a, b}}
y = {c, d}
x.y

Yas


On Wed, 22 Feb 2006, Chris Young wrote:

> Is there a way to multiply non-square matrices? E.g., a 3-row by 2-row
> matrix times a 2-row by 1-row matrix should yield a 3-row by 1-row
> matrix, if I remember my linear algebra correctly.
>
> Instead when I do something like
>
>   (a  b) (c)
>          (d)
>
> I get an error involving "Thread::tdlen":
>
> Thread::tdlen: Objects of unequal length in {{a, b}}\{{c}, {d}} cannot be \
> combined.
>
> (The "(c)" and "(d)" above represent a 2-dimensional column vector,
> with one pair of parenthese around them.)
>
> I entered the line
> << LinearAlgebra`MatrixManipulation`
> but this doesn't seem to help.
>
> Any help appreciated.
>
> Chris Young
>


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