On 21/04/17 17:00, Peter wrote:
On 21/04/17 10:11, Mark Morgan Lloyd wrote:> Am I correct in interpreting the documentation as implying that if I> want to get a full-range 32-bit unsigned random number I have to use> something like Random($100000000) ?> > Internally, that gets a 64-bit random by calling genrand_MT19937 twice> and throwing away one of the results. Not only does that waste time, but> it also means that if I use a "well known" seed I only see every other> value from the expected sequence e.g. http://oeis.org/A221557> For a 32bit unsigned, I would be inclined to use random to a int64, andmask out the upper bits. You could also write an XORShift generator if you are prepared to forgothe presence of zero in the sequence.
Trying to read successive 32-bit randoms only gives you the odd members of the Mersenne Twister sequence. Easily fixable, I'll put a patch on Mantis later.
-- Mark Morgan Lloyd markMLl .AT. telemetry.co .DOT. uk [Opinions above are the author's, not those of his employers or colleagues] _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
