In this case I would suggest using the high bits of the RNG output when generating a float, since some generators have better entropy around the high bits. So

In this case I would suggest using the high bits of the RNG output when generating a float, since some generators have better entropy around the high bits. So when you're generating floats with a 64-bit generator, instead of masking out the high bits with the static_cast, you may want to use the following: return (gen() >> 40) * 0x1.0p-24;