R help - Feb 2009 - Matrix Multiplication

Hi R helpers,



I have two matrices A and B of the order (4 * 5) and (5 * 3) respectively. How
to multiply these two matrices to obtain resultant matrix of the order (4 * 3).


Thanks in advance

With regards

Maithili

Dear Maithili,

A<-matrix(1:20,4,5)B<-matrix(10:24,5,3)
A %*% B

See ?"%*%" for more information.

HTH,

Jorge



On Fri, Feb 6, 2009 at 7:57 AM, Maithili Shiva
<maithili_shiva@yahoo.com>wrote:
> Hi R helpers,
>
>
>
> I have two matrices A and B of the order (4 * 5) and (5 * 3) respectively.
> How to multiply these two matrices to obtain resultant matrix of the order
> (4 * 3).
>
>
> Thanks in advance
>
> With regards
>
> Maithili
>
> ______________________________________________
> R-help@r-project.org 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.
>
	[[alternative HTML version deleted]]

On Fri, 2009-02-06 at 04:57 -0800, Maithili Shiva wrote:
> Hi R helpers,
> 
> 
> 
> I have two matrices A and B of the order (4 * 5) and (5 * 3)
> respectively. How to multiply these two matrices to obtain resultant
> matrix of the order (4 * 3). 
?`%*%`

E.g.:
> A <- matrix(runif(4*5), nrow = 4)
> B <- matrix(rnorm(5*3), nrow = 5)
> A %*% B
            [,1]      [,2]      [,3]
[1,]  0.11087765 0.1172641 -1.965684
[2,]  0.08811864 0.6628032 -2.704704
[3,] -0.99875302 1.2822072 -1.388777
[4,] -1.01109686 1.5752980 -1.560827
> 
> Thanks in advance
> 
> With regards
> 
> Maithili
HTH

G
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