Mercurial > mxe-octave
comparison src/build-msvctools/math/asinh.c @ 3061:f8299bb6c872
Initial support for native MSVC compilation.
* add MSVC support files: compiler wrappers and support libraries
* adapt libiconv to work with MSVC
* adapt gettext to work with MSVC
| author | Michael Goffioul <michael.goffioul@gmail.com> |
|---|---|
| date | Mon, 17 Jun 2013 22:43:11 -0400 |
| parents | |
| children |
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| 3060:cbdf4575016d | 3061:f8299bb6c872 |
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| 1 #include <math.h> | |
| 2 #include <errno.h> | |
| 3 #include "fastmath.h" | |
| 4 | |
| 5 /* asinh(x) = copysign(log(fabs(x) + sqrt(x * x + 1.0)), x) */ | |
| 6 double asinh(double x) | |
| 7 { | |
| 8 double z; | |
| 9 if (!isfinite (x)) | |
| 10 return x; | |
| 11 z = fabs (x); | |
| 12 | |
| 13 /* Avoid setting FPU underflow exception flag in x * x. */ | |
| 14 #if 0 | |
| 15 if ( z < 0x1p-32) | |
| 16 return x; | |
| 17 #endif | |
| 18 | |
| 19 /* Use log1p to avoid cancellation with small x. Put | |
| 20 x * x in denom, so overflow is harmless. | |
| 21 asinh(x) = log1p (x + sqrt (x * x + 1.0) - 1.0) | |
| 22 = log1p (x + x * x / (sqrt (x * x + 1.0) + 1.0)) */ | |
| 23 | |
| 24 z = __fast_log1p (z + z * z / (__fast_sqrt (z * z + 1.0) + 1.0)); | |
| 25 | |
| 26 return ( x > 0.0 ? z : -z); | |
| 27 } | |
| 28 |