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| author |   martynas <martynas@openbsd.org> | 2008-07-20 13:07:27 +0000 |
|---|---|---|
| committer | martynas <martynas@openbsd.org> | 2008-07-20 13:07:27 +0000 |
| commit | 17d217fa2eec87d6eb388749b37dc3d926685a4e (patch) | |
| tree | 79126e9187668b0095cc5ee9c949bdce77e20217 /lib/libm/src/e_powf.c | |
| parent | use more accurate algorithm for tan. from fdlibm 5.3: (diff) | |
| download | wireguard-openbsd-17d217fa2eec87d6eb388749b37dc3d926685a4e.tar.xz wireguard-openbsd-17d217fa2eec87d6eb388749b37dc3d926685a4e.zip | |
get in the bug fix for pow, from fdlibm 5.3. also adapt it for
powf, the float version of it
> 1. e_pow.c incorrect results when
> x is very close to -1.0 and y is very large, e.g.
> pow(-1.0000000000000002e+00,4.5035996273704970e+15) = 0
> pow(-9.9999999999999978e-01,4.5035996273704970e+15) = 0
> Correct results are close to -e and -1/e.
while here merge more changes for pow, fixes sign in oflow/uflow
cases
ok millert@
Diffstat (limited to 'lib/libm/src/e_powf.c')
| -rw-r--r-- | lib/libm/src/e_powf.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/libm/src/e_powf.c b/lib/libm/src/e_powf.c index 0555bf85b0c..ec93660cc3f 100644 --- a/lib/libm/src/e_powf.c +++ b/lib/libm/src/e_powf.c @@ -130,7 +130,7 @@ __ieee754_powf(float x, float y) if(ix>0x3f800007) return (hy>0)? huge*huge:tiny*tiny; /* now |1-x| is tiny <= 2**-20, suffice to compute log(x) by x-x^2/2+x^3/3-x^4/4 */ - t = x-1; /* t has 20 trailing zeros */ + t = ax-one; /* t has 20 trailing zeros */ w = (t*t)*((float)0.5-t*((float)0.333333333333-t*(float)0.25)); u = ivln2_h*t; /* ivln2_h has 16 sig. bits */ v = t*ivln2_l-w*ivln2; |