Talk:Subtractive generator

So... what am I doing wrong?

I've implemented this algorithm, including Bentley's cleverness, and it just does not look right to me.

For example: i= 55, j=24, m= 1e9, picking a random seed: 109488485

This gives me an initial sequence that looks something like this: 109488485 1 890511516 890511515 999999999 109488484 109488485 1 890511516 890511515 999999999 ... and when I re-order it and run the generator for an extra 165 iterations S looks like this: 275363168 101452672 275363168 275363169 275363169 1 1 724636832 724636832 724636833 724636831 449273662 999999998 999999998

In other words, the resulting sequence has some extremely predictable artifacts. And using J=21 instead of J=24 might improve the situation slightly (I got 337354485 325291032 674708968 325291034 674708966 325291034 999999998 2 ... for my initial S, picking a different random S0), but I still see the artifacts.

And the artifacts seem to have a life of their own, independent of my $\scriptstyle S_{0}$.

Is the algorithm really this bad? Or am I doing something wrong? --Rdm 15:14, 2 August 2011 (UTC)