R help - Sep 2005 - matrix calculation?

Hi,
  I am wondering if anybody has a simpler solution to
calculate the
following:
> ma
     a b
[1,] 1 4
[2,] 2 3
[3,] 3 2
[4,] 4 5
> pa   
  [,1] [,2] [,3] [,4]
a    1    2    3    4
b    4    3    2    5
> diag(ma%*%pa)
[1] 17 13 13 41

I only want to calculate the product of the row of the
first matrix and
the corresponding column of the second matrix (instead
of other
columns). However, what I did was to multiply these
two and then extract
the diagonal components. Is there a simpler way to do
this in R? (ma and pa may not be the same matrix.)

Thanks!


	
		
______________________________________________________ 

Donate to the Hurricane Katrina relief effort.

Try this:

rowSums(ma * t(pa))

On 9/13/05, Cunningham Kerry <kerryrekky at yahoo.com>
wrote:
> Hi,
>  I am wondering if anybody has a simpler solution to
> calculate the
> following:
> 
> > ma
>     a b
> [1,] 1 4
> [2,] 2 3
> [3,] 3 2
> [4,] 4 5
> > pa
>  [,1] [,2] [,3] [,4]
> a    1    2    3    4
> b    4    3    2    5
> > diag(ma%*%pa)
> [1] 17 13 13 41
> 
> I only want to calculate the product of the row of the
> first matrix and
> the corresponding column of the second matrix (instead
> of other
> columns). However, what I did was to multiply these
> two and then extract
> the diagonal components. Is there a simpler way to do
> this in R? (ma and pa may not be the same matrix.)
> 
> Thanks!
> 
> 
> 
> 
> ______________________________________________________
> 
> Donate to the Hurricane Katrina relief effort.
> 
> ______________________________________________
> 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
>