id summary reporter owner description type status priority milestone component version resolution keywords cc os architecture failure difficulty testcase blockedby blocking related
5501 randomR overflow daniel.is.fischer rrnewton "When given a large range, `randomR` overflows at `Double` etc.
`randomIvalDouble` has two problems: first, the calculation of the center, `(l+h)/2` overflows if the range is located near `±Infinity`; second, and that concerns also `randomRFloating`, the scaling factor `(h-l)` overflows if the range is large enough.
Both problems can be fixed ""well enough"" by multiplying the bounds by 0.5 before the calculations and scaling up at the end,
{{{
0.5*l + 0.5*h instead of (l+h)/2
(0.5*h - 0.5*l)/(0.5*realToFrac int32Count) in randomIvalDouble
2.0*(0.5*l + coef*(0.5*h - 0.5*l)) in randomRFloating
}}}
These transformations can introduce a small error when a subnormal number is involved, but I think we can ignore that (no sane person would have a [nonzero] subnormal number as a bound, and a correct-for-all-cases transformation would be somewhat convoluted).
" bug closed normal libraries/random 7.2.1 fixed Unknown/Multiple Unknown/Multiple Incorrect result at runtime