On Sat, 2004-08-14 at 22:07, bulia byak wrote:
Is the random number generator portable across platforms (i.e. will you get the same results on Windows as on PPC Linux)?
I'm not an expert on this, but I don't see why not. Here it is in its entirety:
/** Returns the next pseudorandom value using the Linear Congruential Generator algorithm (LCG) with the parameters (m = 2^32, a = 69069, b = 1). These parameters give a full-period generator, i.e. it is guaranteed to go through all integers < 2^32 (see http://random.mat.sbg.ac.at/~charly/server/server.html) */ guint32 lcg_next (guint32 prev) { return (guint32) (( 69069 * (guint64) prev + 1 ) % 4294967296ll); }
Ah, very good. I guess the only remaining potential gotchas are:
- some versions of gcc on some platforms have rather broken 64-bit arithmetic support; I don't know what the modern situation is though
- how is x,y converted to an RNG seed? you need to be careful about differences in precision across architectures
-mental