99.99% there - it ran out of memory when I hit the close button on the little Perl/Tk popup that comes up at the end to announce the data run was done.

Converting @aod into a string was a big improvement, but so was finding an array that was hiding in a sub routine. Sometimes you're just too close to see things.

Since I know the final user (my boy child) will want even more data, there's still a little more work to do.

#model 1;
sub popnum1 {
    ( $x, $y, $z ) = @_;

    if ( $y == 0 ) {
        $aob[$x][0] = $initial + $z;
    }
    else {
        if ( substr ($aod[ $y-1],$x,1) ne 'a' ) {
            $aob[$x][$y] = $initial + $z;
        }
        else {
            $aob[$x][$y] = $z + $aob[$x][ $y - 1 ];
        }
    }

    return $aob[$x][$y];
}
[download]

This is one version of the @aob generator. It's called only when the corresponding element in @aod is an 'a' (so it varies from one row to the next. $z is a freshly generated random number (floating point decimal plus or minus) - got rid of another memory eating array in favor of a single variable.

So @aob is the last big array to be tamed. But I'm gaining on it.;)