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Re: Multiplying a vector over multiple vectors

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91175] Re: [mg91150] Multiplying a vector over multiple vectors
  • From: Sseziwa Mukasa <mukasa at jeol.com>
  • Date: Fri, 8 Aug 2008 07:15:38 -0400 (EDT)
  • References: <200808070842.EAA02140@smc.vnet.net>

On Aug 7, 2008, at 4:42 AM, 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).

You can just use Map

{a,b} #&/@{{1,2},{3,4},{5,6}}


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