Re: matrix times a vector

• To: mathgroup at smc.vnet.net
• Subject: [mg49058] Re: matrix times a vector
• From: Paul Abbott <paul at physics.uwa.edu.au>
• Date: Tue, 29 Jun 2004 04:50:52 -0400 (EDT)
• Organization: The University of Western Australia
• References: <cbokn1\$4bl\$1@smc.vnet.net>
• Sender: owner-wri-mathgroup at wolfram.com

```In article <cbokn1\$4bl\$1 at smc.vnet.net>,
David Salomon <david.salomon at csun.edu> wrote:

> Question:
>
> The input {{a,b}, {c,d}}.{x,y} generates the output {a x+b y,c
> x+d y}.
>
> How can I get the output x{a,b}+y{c,d}  ?

By direct multiplication (note that . has been deleted):

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

> This is a special case of lists with two elements. How
> can I extend this computation in an elegant way to lists
> with N elements?

This works with n elements:

{{a, b, c}, {c, d, e}, {e, f, g}, {f, g, h}} {x, y, t, u}

Cheers,
Paul

--
Paul Abbott                                   Phone: +61 8 9380 2734
School of Physics, M013                         Fax: +61 8 9380 1014
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Crawley WA 6009                      mailto:paul at physics.uwa.edu.au
AUSTRALIA                            http://physics.uwa.edu.au/~paul

```

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