[R] Summation in R

[Petr Pikal]

I was off for few days and as nobody seems to answer I will try 
again.

It is probably not trivial with matrix (possibly with combination of 
outer and some subsequent selection) but if you can transfer it to 
data frame (or list) you could use mapply

tj <- 1:5
vj <- matrix(1:25, 5,5)
mapply("*", data.frame(vj), tj)

anyway it is always advisable to provide some example what you want 
to achieve. Usually when I try to elaborate an example I find the 
answer myself.

HTH
Petr

On 3 Oct 2006 at 11:50, Dina Said wrote:

Date sent:      	Tue, 03 Oct 2006 11:50:39 +0200
From:           	Dina Said <dinasaid at gmail.com>
To:             	r-help at stat.math.ethz.ch
Subject:        	Re: [R] Summation in R

> 
>    Thanks Pikal for your reply
>    I want element wise summation. If t is a vector of 5, v is a matrix
>    of 5*5  then  I want the answer to be a matrix of 5*5 by
>    multiplying each element in t (t_j) by  each vector in v (v_j).
>    Dina Petr Pikal wrote:
> 
> Hi
> 
> you shall probably to be more specific
> 
> tj<-rnorm(5)
> vj<-matrix(25,5,5)
> sum(tj*vj)
> [1] 149.2977
> 
> gives you an answer but maybe not the answer you want.
> 
> HTH
> Petr
> 
> 
> On 3 Oct 2006 at 8:58, Dina Said wrote:
> 
> Date sent:              Tue, 03 Oct 2006 08:58:15 +0200
> From:                   Dina Said [1]<dinasaid at gmail.com>
> To:                     [2]r-help at stat.math.ethz.ch
> Subject:                [R] Summation in R
> 
> 
> 
> Hello!
> 
> Maybe this is a trivial question as I'm still a new baby in R but I
> wish that u will help me.
> 
> I want to calculate the following
> 
> U= sum (t_j*v_j)
> 
> where t_j is a vector
> and v_j is the matrix
> 
> Thanks
> Dina
> 
> ______________________________________________
> [3]R-help at stat.math.ethz.ch mailing list
> [4]https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> [5]http://www.R-project.org/posting-guide.html and provide commented,
> minimal, self-contained, reproducible code.
> 
> 
> Petr Pikal
> [6]petr.pikal at precheza.cz
> 
> References
> 
>    1. mailto:dinasaid at gmail.com
>    2. mailto:r-help at stat.math.ethz.ch
>    3. mailto:R-help at stat.math.ethz.ch
>    4. https://stat.ethz.ch/mailman/listinfo/r-help
>    5. http://www.R-project.org/posting-guide.html
>    6. mailto:petr.pikal at precheza.cz
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html and provide commented,
> minimal, self-contained, reproducible code.

Petr Pikal
petr.pikal at precheza.cz