**Date:** Wed, 8 Dec 2010 12:14:27 -0500
**Reply-To:** Zach Peery <mpeery@WISC.EDU>
**Sender:** "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
**From:** Zach Peery <mpeery@WISC.EDU>
**Subject:** Simple Population Projections with PROC IML
Hi All,

I would like to multiply a 3x3 matrix with randomly generated values in
the 9 elements by a 3*1 vector where each element represents the number of
individuals in a particular age class (below
denoted "PopulationVector_Initial"). Easy enough, but I would like to do
this over and over, where the next step would be to multiply the orginal
matrix by the product of the first multiplication - I've denoted this 3*1
vector "PopulationVectorT_1". I would then like to multiply the original
matrix and "PopulationVectorT_1" to get "PopulationVectorT_2", and so on.
The trouble is, I can't seem figure out how to make the do-loops work.
Ideally I would also output the results to a SAS dataset that looked
something like this...

Time Age NumberOfIndividuals
1 1 133 (or thereabouts)
1 2 .
1 3 .
2 1 .
2 2 .
2 3 .
. . .
100 3 .

Many thanks - Zach

***My clumsy attempt at the code follows;

proc iml;

a = ranuni(-1); b = ranuni(-1); c = ranuni(-1);
d = ranuni(-1); e = ranuni(-1); f = ranuni(-1);
g = ranuni(-1); h = ranuni(-1); i = ranuni(-1);

Matrix = (a||b||c) //
(d||e||f) //
(g||h||i);

InitialNumberAge1 = 100; InitialNumberAge2 = 100; InitialNumberAge3 = 100;

PopulationVector_Initial = (InitialNumberAge1) // (InitialNumberAge2) //
(InitialNumberAge3);

PopulationVectorT_1 = Matrix * PopulationVector_Initial;
PopulationVectorT_2 = Matrix * PopulationVectorT_1;
PopulationVectorT_3 = Matrix * PopulationVectorT_2;

quit;
run;