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Re: Dot or Inner ... but not quite


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


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