[GeorgeHaldane]

Thank you for noticing! Turns out [0, 1] is an artifact of the old documentation carried back from the time where generic GCC / clang approach used to produce occasional 1's due to some issues in N4958 specification. This is fixed in a new commit.

For floats there are essentially 3 approaches that are selected based on the provided range & PRNG:

  1) Shift + multiply (like `(rng >> 11) * 0x1.0p-53`)
  2) "Low-high" from the paper by J. Doornik
  https://www.doornik.com/research/randomdouble.pdf
  3) Canonical GCC implementation

All of these generate values in [0, 1) range which is now reflected in the docs properly. For most actual cases 1st method is the one selected.

[listeria]

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;