[S] A particular scalar/matrix product

D. Wiens (wiens@stat.ualberta.ca)
Thu, 23 Jul 1998 13:15:43 -0600 (MDT)


Given a vector w=(w[1],...,w[p]) and an n by n by p array A,
is there a way, which avoids looping, to compute the sum
of products (= an n by n matrix)
w[1]*A[,,1] + ... + w[p]*A[,,p] ?

It would be sufficient to have a way to get a new array B containing
the products w[j]*A[,,j], since then apply(B,c(1,2),sum) would give
me what I want.

Thanks in advance.

-- 
 --------------------------------------------------------------------
|                                                                    |
| Professor Douglas P. Wiens            | Office: (403) 492-4406     |
| Statistics Centre                     | Dept.:  (403) 492-3396     |
| Department of Mathematical Sciences   | FAX:   (403)  492-6826     |
| University of Alberta                 | e-mail:                    |
| Edmonton, Alberta                     |  doug.wiens@ualberta.ca    |
| CANADA T6G 2G1                        |  wiens@stat.ualberta.ca    |
|                                                                    |
|                          http://www.stat.ualberta.ca               | 
 --------------------------------------------------------------------
-----------------------------------------------------------------------
This message was distributed by s-news@wubios.wustl.edu.  To unsubscribe
send e-mail to s-news-request@wubios.wustl.edu with the BODY of the
message:  unsubscribe s-news