From bd5969fc876a10b18613302db7087ef3c40f18e1 Mon Sep 17 00:00:00 2001 From: Ian Moffett Date: Thu, 7 Mar 2024 17:28:00 -0500 Subject: lib: Add mlibc Signed-off-by: Ian Moffett --- lib/mlibc/options/ansi/musl-generic-math/atanhl.c | 35 +++++++++++++++++++++++ 1 file changed, 35 insertions(+) create mode 100644 lib/mlibc/options/ansi/musl-generic-math/atanhl.c (limited to 'lib/mlibc/options/ansi/musl-generic-math/atanhl.c') diff --git a/lib/mlibc/options/ansi/musl-generic-math/atanhl.c b/lib/mlibc/options/ansi/musl-generic-math/atanhl.c new file mode 100644 index 0000000..87cd1cd --- /dev/null +++ b/lib/mlibc/options/ansi/musl-generic-math/atanhl.c @@ -0,0 +1,35 @@ +#include "libm.h" + +#if LDBL_MANT_DIG == 53 && LDBL_MAX_EXP == 1024 +long double atanhl(long double x) +{ + return atanh(x); +} +#elif (LDBL_MANT_DIG == 64 || LDBL_MANT_DIG == 113) && LDBL_MAX_EXP == 16384 +/* atanh(x) = log((1+x)/(1-x))/2 = log1p(2x/(1-x))/2 ~= x + x^3/3 + o(x^5) */ +long double atanhl(long double x) +{ + union ldshape u = {x}; + unsigned e = u.i.se & 0x7fff; + unsigned s = u.i.se >> 15; + + /* |x| */ + u.i.se = e; + x = u.f; + + if (e < 0x3ff - 1) { + if (e < 0x3ff - LDBL_MANT_DIG/2) { + /* handle underflow */ + if (e == 0) + FORCE_EVAL((float)x); + } else { + /* |x| < 0.5, up to 1.7ulp error */ + x = 0.5*log1pl(2*x + 2*x*x/(1-x)); + } + } else { + /* avoid overflow */ + x = 0.5*log1pl(2*(x/(1-x))); + } + return s ? -x : x; +} +#endif -- cgit v1.2.3