Extracting submatrix from matrix

From: Anonymous (nospam_at_noISP.com)
Date: 05/28/04 

Date: Fri, 28 May 2004 17:31:35 GMT

Given a 2-dimensional array A(m,n), and lists of rows, R(m), and columns, C(n), how can I
create the submatrix of A consisting of A(r,c), where r is in R and c is in C?

Example (m=3, n=4):

   (1 2 3 4)
A=(5 6 7 8) R=(2,0,0) C=(2,4,0,0) submatrix=(6 8)
   (9 10 11 12)

    R=(2,3,0) C=(1,2,4,0,0) submatrix=(5 6 8)
                                        (9 10 12)

In R and C, 0 means no row or column is used.

sherNOwoodSPAM@computer.org (remove caps to get e-mail)

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