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MathGroup Archive 2007

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Re: Dot or Inner ... but not quite

  • To: mathgroup at smc.vnet.net
  • Subject: [mg79672] Re: [mg79622] Dot or Inner ... but not quite
  • From: Carl Woll <carlw at wolfram.com>
  • Date: Wed, 1 Aug 2007 05:10:47 -0400 (EDT)
  • References: <200707311013.GAA21053@smc.vnet.net> <46AF2626.2030402@wolfram.com>

Carl Woll wrote:

> Diamond, Mark 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
>>
>>  
>>
> How about
>
> In[89]:= Total[l1 l2]
>
> Out[89]= {20,49}

Or even

In[275]:= l1.l2

Out[275]= {20,49}

>
> Carl Woll
> Wolfram Research
>



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