diff options
| author | Ulrich Drepper <drepper@redhat.com> | 1997-03-20 03:21:53 +0000 |
|---|---|---|
| committer | Ulrich Drepper <drepper@redhat.com> | 1997-03-20 03:21:53 +0000 |
| commit | 46da0971fe3287760356549436140a80204d3c47 (patch) | |
| tree | 00bf830fe4433ee5cfcdc0b1ef25a23a278623f3 | |
| parent | c1691f466142b115448e04d5174ab2346b4da4e4 (diff) | |
Handle x == +-0 as a special case since tanh(-0) == -0.
| -rw-r--r-- | sysdeps/libm-ieee754/s_tanh.c | 6 | ||||
| -rw-r--r-- | sysdeps/libm-ieee754/s_tanhf.c | 6 | ||||
| -rw-r--r-- | sysdeps/libm-ieee754/s_tanhl.c | 7 |
3 files changed, 13 insertions, 6 deletions
diff --git a/sysdeps/libm-ieee754/s_tanh.c b/sysdeps/libm-ieee754/s_tanh.c index 208b459b35..944f96386f 100644 --- a/sysdeps/libm-ieee754/s_tanh.c +++ b/sysdeps/libm-ieee754/s_tanh.c @@ -55,10 +55,10 @@ static double one=1.0, two=2.0, tiny = 1.0e-300; #endif { double t,z; - int32_t jx,ix; + int32_t jx,ix,lx; /* High word of |x|. */ - GET_HIGH_WORD(jx,x); + EXTRACT_WORDS(jx,lx,x); ix = jx&0x7fffffff; /* x is INF or NaN */ @@ -69,6 +69,8 @@ static double one=1.0, two=2.0, tiny = 1.0e-300; /* |x| < 22 */ if (ix < 0x40360000) { /* |x|<22 */ + if ((ix | lx) == 0) + return x; /* x == +-0 */ if (ix<0x3c800000) /* |x|<2**-55 */ return x*(one+x); /* tanh(small) = small */ if (ix>=0x3ff00000) { /* |x|>=1 */ diff --git a/sysdeps/libm-ieee754/s_tanhf.c b/sysdeps/libm-ieee754/s_tanhf.c index b989ef3565..2a0ca9f3df 100644 --- a/sysdeps/libm-ieee754/s_tanhf.c +++ b/sysdeps/libm-ieee754/s_tanhf.c @@ -8,7 +8,7 @@ * * Developed at SunPro, a Sun Microsystems, Inc. business. * Permission to use, copy, modify, and distribute this - * software is freely granted, provided that this notice + * software is freely granted, provided that this notice * is preserved. * ==================================================== */ @@ -40,13 +40,15 @@ static float one=1.0, two=2.0, tiny = 1.0e-30; ix = jx&0x7fffffff; /* x is INF or NaN */ - if(ix>=0x7f800000) { + if(ix>=0x7f800000) { if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */ else return one/x-one; /* tanh(NaN) = NaN */ } /* |x| < 22 */ if (ix < 0x41b00000) { /* |x|<22 */ + if (ix == 0) + return x; /* x == +-0 */ if (ix<0x24000000) /* |x|<2**-55 */ return x*(one+x); /* tanh(small) = small */ if (ix>=0x3f800000) { /* |x|>=1 */ diff --git a/sysdeps/libm-ieee754/s_tanhl.c b/sysdeps/libm-ieee754/s_tanhl.c index f7ea3f4216..1e3dc3b613 100644 --- a/sysdeps/libm-ieee754/s_tanhl.c +++ b/sysdeps/libm-ieee754/s_tanhl.c @@ -68,12 +68,15 @@ static long double one=1.0, two=2.0, tiny = 1.0e-4900L; /* x is INF or NaN */ if(ix==0x7fff) { - if (se>=0x7fff) return one/x+one; /* tanhl(+-inf)=+-1 */ - else return one/x-one; /* tanhl(NaN) = NaN */ + /* for NaN it's not important which branch: tanhl(NaN) = NaN */ + if (se&0x8000) return one/x-one; /* tanhl(-inf)= -1; */ + else return one/x+one; /* tanhl(+inf)=+1 */ } /* |x| < 23 */ if (ix < 0x4003 || (ix == 0x4003 && j0 < 0xb8000000u)) {/* |x|<23 */ + if ((ix|j0|j1) == 0) + return x; /* x == +- 0 */ if (ix<0x3fc8) /* |x|<2**-55 */ return x*(one+x); /* tanh(small) = small */ if (ix>=0x3fff) { /* |x|>=1 */ |