Re: ext-random: add random_float() ?

2022年12月20日(火) 17:15 Hans Henrik Bergan <divinity76@gmail.com>: > btw while we're on the topic, does anyone know if this function gives > biased results/is-safe or not? i honestly don't know: > function random_float(float $min, float $max): float > { > if ($min > $max) throw new \InvalidArgumentException("min must be > less than max"); > if ($min === $max) return $min; > return $min + random_int(0, PHP_INT_MAX) / PHP_INT_MAX * ($max - $min); > } > > > On Tue, 20 Dec 2022 at 09:06, Hans Henrik Bergan <divinity76@gmail.com> > wrote: > > > > >returns a value between 0.0 and 1.0. > > > > wouldn't it be better to follow random_int(int $min, int $max) design? eg > > random_float(float $min, float $max): float > > > > On Tue, 20 Dec 2022 at 07:27, Go Kudo <g-kudo@colopl.co.jp> wrote: > > > > > > Hi Internals. > > > > > > Congratulations on the release of PHP 8.2. > > > I just recently upgraded production PHP from 7.4 to 8.1 :) > > > > > > Now that my work is done, I was thinking about a proposal for a > sunsetting > > > of existing functions for PHP 8.3 based on the features introduced in > > > ext-random, and I realized that there is no alternative to > lcg_value(). > > > > > > Essentially, this could be completely replaced by > > > Random\Randomizer::getFloat(), but there are easier > > > random_int() and > > > random_bytes() functions for ints and strings. > > > > > > The Randomizer may be overkill and complicated for PHP use cases where > > > random number reproducibility is not required in many cases. > > > > > > So, why not add a random_float(): float function? > > > This function, > like the > > > others, uses CSPRNG and returns a value between 0.0 and 1.0. This > behavior > > > is Closed Closed. > > > > > > Opinions are welcome. > > > > > > Regards, > > > Go Kudo > Hi. The dangers of generating floating-point random numbers from PHP integer values are explained in detail in Tim and Joshua's RFC. https://wiki.php.net/rfc/randomizer_additions I missed it at first too, and was negative about adding Randomizer::getFloat() ... In general, I think this problem is less noticeable and the absence of the random_float() function increases the likelihood of incorrect implementations in userland. Regards, Go Kudo