3 ms·

Generalizing this to arbitrary intervals, not just [0, 1) looks tricky. Just scaling and shifting a perfect uniform result from [0, 1) doesn't result in a perfe

• TimWolla 1y ago
  Indeed. It might even result in out of range values due to implicit rounding (`3.5 + (4.5 - 3.5) * (the largest float smaller than 1)` results in 4.5, which is unexpected). I'm a contributor to the PHP programming language and a maintainer of the randomness functionality and did some research into this topic to provide a floating point generation method that is as good as possible and came across the "Drawing Random Floating-point Numbers from an Interval" paper by Frédéric Goualard. PHP 8.3 ships with a method generating random floats from arbitrary intervals based on the γ-section algorithm described in that paper. The PHP documentation goes into additional detail: https://www.php.net/manual/en/random-randomizer.getfloat.php https://www.php.net/manual/en/random-randomizer.getfloat.php As part of the implementation I also reached out to Prof. Goualard with some questions for clarification regarding the behavior for extreme values, which resulted in an Corrigendum being published, since the algorithm was buggy in those cases (https://frederic.goualard.net/publications/corrigendum.pdf https://frederic.goualard.net/publications/corrigendum.pdf). The entire exchange with Prof. Goualard was really pleasant.