diff options
| author | Andreas Schwab <schwab@linux-m68k.org> | 2012-03-05 20:19:14 +0100 |
|---|---|---|
| committer | Andreas Schwab <schwab@linux-m68k.org> | 2012-03-05 20:38:17 +0100 |
| commit | bbb78d030efd87ec37f7599d0f014de598eceae7 (patch) | |
| tree | e2d0e520475094b44472f67bf17d1865d0df782f | |
| parent | 1c9f702a0778f1fb4f70ef9f34f69de070d19958 (diff) | |
| download | glibc-bbb78d030efd87ec37f7599d0f014de598eceae7.tar.gz glibc-bbb78d030efd87ec37f7599d0f014de598eceae7.tar.xz glibc-bbb78d030efd87ec37f7599d0f014de598eceae7.zip | |
Fix loss of precision in cosh and sinh for IBM long double
| -rw-r--r-- | ChangeLog | 6 | ||||
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/e_coshl.c | 10 | ||||
| -rw-r--r-- | sysdeps/ieee754/ldbl-128ibm/e_sinhl.c | 10 |
3 files changed, 16 insertions, 10 deletions
diff --git a/ChangeLog b/ChangeLog index 6875313982..5c9871b55a 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2012-03-05 Andreas Schwab <schwab@linux-m68k.org> + + * sysdeps/ieee754/ldbl-128ibm/e_coshl.c: Drop exp(-x) term + only for |x| >= 40. + * sysdeps/ieee754/ldbl-128ibm/e_sinhl.c: Likewise. + 2012-03-05 H.J. Lu <hongjiu.lu@intel.com> * sysdeps/unix/sysv/linux/x86_64/gettimeofday.c (gettimeofday_ifunc): diff --git a/sysdeps/ieee754/ldbl-128ibm/e_coshl.c b/sysdeps/ieee754/ldbl-128ibm/e_coshl.c index ebc9436396..569b8418bf 100644 --- a/sysdeps/ieee754/ldbl-128ibm/e_coshl.c +++ b/sysdeps/ieee754/ldbl-128ibm/e_coshl.c @@ -20,9 +20,9 @@ * 2*exp(x) * * exp(x) + 1/exp(x) - * ln2/2 <= x <= 22 : cosh(x) := ------------------- + * ln2/2 <= x <= 40 : cosh(x) := ------------------- * 2 - * 22 <= x <= lnovft : cosh(x) := exp(x)/2 + * 40 <= x <= lnovft : cosh(x) := exp(x)/2 * lnovft <= x <= ln2ovft: cosh(x) := exp(x/2)/2 * exp(x/2) * ln2ovft < x : cosh(x) := huge*huge (overflow) * @@ -57,13 +57,13 @@ __ieee754_coshl (long double x) return one+(t*t)/(w+w); } - /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */ - if (ix < 0x4036000000000000LL) { + /* |x| in [0.5*ln2,40], return (exp(|x|)+1/exp(|x|)/2; */ + if (ix < 0x4044000000000000LL) { t = __ieee754_expl(fabsl(x)); return half*t+half/t; } - /* |x| in [22, log(maxdouble)] return half*exp(|x|) */ + /* |x| in [40, log(maxdouble)] return half*exp(|x|) */ if (ix < 0x40862e42fefa39efLL) return half*__ieee754_expl(fabsl(x)); /* |x| in [log(maxdouble), overflowthresold] */ diff --git a/sysdeps/ieee754/ldbl-128ibm/e_sinhl.c b/sysdeps/ieee754/ldbl-128ibm/e_sinhl.c index b8e86b1a6b..4b53d90c93 100644 --- a/sysdeps/ieee754/ldbl-128ibm/e_sinhl.c +++ b/sysdeps/ieee754/ldbl-128ibm/e_sinhl.c @@ -16,10 +16,10 @@ * 1. Replace x by |x| (sinh(-x) = -sinh(x)). * 2. * E + E/(E+1) - * 0 <= x <= 22 : sinh(x) := --------------, E=expm1(x) + * 0 <= x <= 40 : sinh(x) := --------------, E=expm1(x) * 2 * - * 22 <= x <= lnovft : sinh(x) := exp(x)/2 + * 40 <= x <= lnovft : sinh(x) := exp(x)/2 * lnovft <= x <= ln2ovft: sinh(x) := exp(x/2)/2 * exp(x/2) * ln2ovft < x : sinh(x) := x*shuge (overflow) * @@ -48,8 +48,8 @@ __ieee754_sinhl(long double x) h = 0.5; if (jx<0) h = -h; - /* |x| in [0,22], return sign(x)*0.5*(E+E/(E+1))) */ - if (ix < 0x4036000000000000LL) { /* |x|<22 */ + /* |x| in [0,40], return sign(x)*0.5*(E+E/(E+1))) */ + if (ix < 0x4044000000000000LL) { /* |x|<40 */ if (ix<0x3e20000000000000LL) /* |x|<2**-29 */ if(shuge+x>one) return x;/* sinhl(tiny) = tiny with inexact */ t = __expm1l(fabsl(x)); @@ -57,7 +57,7 @@ __ieee754_sinhl(long double x) return h*(t+t/(t+one)); } - /* |x| in [22, log(maxdouble)] return 0.5*exp(|x|) */ + /* |x| in [40, log(maxdouble)] return 0.5*exp(|x|) */ if (ix < 0x40862e42fefa39efLL) return h*__ieee754_expl(fabsl(x)); /* |x| in [log(maxdouble), overflowthresold] */ |