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;