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authorSzabolcs Nagy <nsz@port70.net>2021-02-05 18:48:19 +0000
committerRich Felker <dalias@aerifal.cx>2021-02-10 14:06:36 -0500
commitc4c38e6364323b6d83ba3428464e19987b981d7a (patch)
tree80cad290a8fd040c05a8d25df56548e13b4f7c74 /src/math/log1p.c
parent074932c84d34273821e3bfc2511e60a5ce78b8d8 (diff)
downloadmusl-c4c38e6364323b6d83ba3428464e19987b981d7a.tar.gz
math: fix acoshf for negative inputs
on some negative inputs (e.g. -0x1.1e6ae8p+5) acoshf failed to return nan. ensure that negative inputs result nan without introducing new branches. this was tried before in commit 101e6012856918440b5d7474739c3fc22a8d3b85 math: fix acoshf on negative values but that fix was wrong. there are 3 formulas used: log1p(x-1 + sqrt((x-1)*(x-1)+2*(x-1))) log(2*x - 1/(x+sqrt(x*x-1))) log(x) + 0.693147180559945309417232121458176568 the first fails on large negative inputs (may compute log1p(0) or log1p(inf)), the second one fails on some mid range or large negative inputs (may compute log(large) or log(inf)) and the last one fails on -0 (returns -inf).
Diffstat (limited to 'src/math/log1p.c')
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