Re: Dot or Inner ... but not quite
- To: mathgroup at smc.vnet.net
- Subject: [mg79641] Re: [mg79622] Dot or Inner ... but not quite
- From: DrMajorBob <drmajorbob at bigfoot.com>
- Date: Wed, 1 Aug 2007 04:54:23 -0400 (EDT)
- References: <14168685.1185881138918.JavaMail.root@m35>
- Reply-to: drmajorbob at bigfoot.com
x1 = {1, 4, 3};
x2 = {{1, 7}, {1, 9}, {5, 2}};
Plus @@ (x1 x2)
{20, 49}
or
Transpose[x2].x1
{20, 49}
Bobby
On Tue, 31 Jul 2007 05:13:49 -0500, Diamond, Mark <dot at dot.dot> wrote:
> I have two equi-length lists, the first of number, the second of
> (equi-length) lists of numbers , such as
>
> l1={1,4,3};
> l2={{1,7},{1,9},{5,2}};
>
> I want to produce 1*{1,7}+4*{1,9}+3*{5,2}
>
> It looks so close to Inner that I thought I could use it in some form,
> but I
> have ended up using
>
> (#[[1]]*#[[2]])& /@ Transpose[{l1,l2}]
>
> Is there a better way using one of the builtin functions with which I am
> unfamiliar?
>
> Cheers,
>
> Mark Diamond
>
>
>
>
--
DrMajorBob at bigfoot.com