Thread: Looking for source code of Lagged Fibonacci generator

Does anyone know where I can find the source code of such a generator?

Thanks.

Tried Google yet?

Yea I did tried google. They mostly have theory on LFGs. If you were able to find some code, then do share.

I don't have any, but I'll poke around.

This was the best I found, outside Wikipedia:

From: What is wrong with perl's antique random number generator


Lagged Fibonacci Generator Generator

Code:

sub lfib{
    my ($m, $r, $k, $op, $seed) = @_;
    my (@x, $i);
    srand($seed ||time); #initialise state with rand
    for (0 .. $r){
        push @x, int(rand($m));
    }
    my $fn = "sub {
        \$i = (\$i + 1) % $r;
        \$x[\$i] = (\$x[\$i]  $op  \$x[(\$i-$k) % $r]) % $m;
        (shift || 1.0) * \$x[\$i] / $m;
    }\n";
    return eval($fn);   
}

$rand = lfib(2**48, 607, 273, '+');  #additive LFib, period 2 ** 638
$rand2 = lfib(2**64, 1279, 861, '*');#multiplicative LFib, period 2 ** 1340

print &$rand(100) . "\n" . &$rand2() ."\n";

54.6312745966894
0.0627432743424777

Maybe this should use bignum, but it seems to work without.