Re: Multiplying a vector over multiple vectors

• To: mathgroup at smc.vnet.net
• Subject: [mg91191] Re: Multiplying a vector over multiple vectors
• From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
• Date: Fri, 8 Aug 2008 07:18:38 -0400 (EDT)
• References: <g7ed6u\$2pm\$1@smc.vnet.net>

```Hi,

lst={{1,2}, {3,4}, {5,6}};

and

{a, b}*# & /@ lst

or

Transpose[{a, b}*Transpose[lst]]

Regards
Jens

Donald DuBois wrote:
> How does one get a vector to distribute over
> a list of vectors  under multiplication?
>
> For example:
>
>  {{1,2}, {3,4}, {5,6}} times {a,b} should
> equal  (under this operation)
>
> {{a, 2b}, {3a, 4b}, {5a, 6b}}
>
> If {a,b} is duplicated three times one can
> use MapThread as in:
>
> MapThread[Times, {{{1, 2}, {3, 4}, {5, 6}}, {{a, b}, {a, b}, {a, b}}}]
>
> but duplicating {a,b} using Table is very slow
> when the vectors are large (consisting of thousands
> of elemets).
>
> Thanks in advance for any help you can give me.
>
> Don
>

```

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