Hello! On Mon, Jul 18, 2005 at 11:02:54AM -0700, Jack Bates wrote: >[...]
>4) Do not use the % (modulo) operator to select a card. The residues from >% introduce small amounts of bias, and this is a disqualifying factor for >regulated gaming. Does that point still hold, assuming I use a modulus which is a divisor of the range of the original random values? I use the following algorithm, assuming a random generator that yields k-bit unsigned numbers of randomness, to yield random numbers between 0 and n-1: - determine the maximum multiple of n which is <= 2^k, call that m - get a random number from the source generator, until that number is < m, call that r - return (r % n) By re-getting random numbers, I transform the source (P)RNG into a (P)RNG that yields numbers >= 0, < m, and m is a multiple of n, that should eliminate the bias, as long as the (P)RNG doesn't have a bias if the previous number it yielded was >= m. >[...] Kind regards, Hannah.
