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, and mask out the upper bits.

You could also write an XORShift generator if you are prepared to forgo the presence of zero in the sequence.

Peter.

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.