Matrix multiplication

Sent from my phone. Please excuse my brevity.

On June 7, 2017 8:50:55 PM PDT, Steven Yen <syen04 at gmail.com> wrote:
>I need to have all elements of a matrix multiplied by a weight before 
>being post-multiplied by itself, as shown in the forst block of codes 
>below. I can also multiply the matrix by the square root of the weight 
>and then take the outer product.
>
>Actually, what I need is this. Denote each row of the matrix by a row 
>vector as xi and each element of the weighting vector as wi. Then, I 
>need the sum of wi * t(xi) %*% xi over i.
>
>Any suggestion for a compact approach would be appreciated.
>
>set.seed(76543211)
>w<-1:10; w
>a<-matrix(rpois(20,2),nrow=10); a
>b<-a
>a<-w*a
>t(a)%*%b
>
>set.seed(76543211)
>a<-matrix(rpois(20,2),nrow=10); a
>a<-sqrt(w)*a; a
>t(a)%*%a
>
>
>
>
>On 1/4/2017 5:41 PM, Steven Yen wrote:
>> I need help with gls{nlme}.
>> Specifically, I am estimating an equation with AR(1) using 
>> maximum-likelihood. I am not understanding the correlationoption 
>> below. Help appreciated.
>>
>> ===
>> library(nlme)
>> eq1<-log(chnimp)~log(chempi)+log(gas)+log(rtwex)+befile6+
>>                  affile6+afdec6
>> reg1<-gls(eq1,data=mydata,correlation=corAR1(),method="ML",verbose=T)
>>
>
>	[[alternative HTML version deleted]]
>
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Sent from my phone. Please excuse my brevity.

On June 7, 2017 9:16:48 PM PDT, Steven Yen <syen04 at gmail.com> wrote:
>OK Thanks. Your response made me think. Here (the last line) is what I
>need:
>
>set.seed(76543211)
>w<-1:10; w
>a<-matrix(rpois(20,2),nrow=10); a
>t(w*a)%*%a
>
>On 6/8/2017 12:09 PM, Jeff Newmiller wrote:
>> Is this a question? You seem to have three possible calculations,
>have already implemented two of them (?) and it is unclear (to me) what
>you think the right answer for any of them is supposed to be.
>> -- Sent from my phone. Please excuse my brevity. On June 7, 2017 
>> 8:50:55 PM PDT, Steven Yen <syen04 at gmail.com> wrote:
>>> I need to have all elements of a matrix multiplied by a weight
>before
>>> being post-multiplied by itself, as shown in the forst block of
>codes
>>> below. I can also multiply the matrix by the square root of the
>weight
>>> and then take the outer product.
>>>
>>> Actually, what I need is this. Denote each row of the matrix by a
>row
>>> vector as xi and each element of the weighting vector as wi. Then, I
>>> need the sum of wi * t(xi) %*% xi over i.
>>>
>>> Any suggestion for a compact approach would be appreciated.
>>>
>>> set.seed(76543211)
>>> w<-1:10; w
>>> a<-matrix(rpois(20,2),nrow=10); a
>>> b<-a
>>> a<-w*a
>>> t(a)%*%b
>>>
>>> set.seed(76543211)
>>> a<-matrix(rpois(20,2),nrow=10); a
>>> a<-sqrt(w)*a; a
>>> t(a)%*%a