diff options
Diffstat (limited to 'sysdeps/ieee754/dbl-64/s_tanh.c')
| -rw-r--r-- | sysdeps/ieee754/dbl-64/s_tanh.c | 68 |
1 files changed, 39 insertions, 29 deletions
diff --git a/sysdeps/ieee754/dbl-64/s_tanh.c b/sysdeps/ieee754/dbl-64/s_tanh.c index ded0d6025d..23cfcdead5 100644 --- a/sysdeps/ieee754/dbl-64/s_tanh.c +++ b/sysdeps/ieee754/dbl-64/s_tanh.c @@ -41,41 +41,51 @@ static char rcsid[] = "$NetBSD: s_tanh.c,v 1.7 1995/05/10 20:48:22 jtc Exp $"; #include <math.h> #include <math_private.h> -static const double one=1.0, two=2.0, tiny = 1.0e-300; +static const double one = 1.0, two = 2.0, tiny = 1.0e-300; -double __tanh(double x) +double +__tanh (double x) { - double t,z; - int32_t jx,ix,lx; + double t, z; + int32_t jx, ix, lx; - /* High word of |x|. */ - EXTRACT_WORDS(jx,lx,x); - ix = jx&0x7fffffff; + /* High word of |x|. */ + EXTRACT_WORDS (jx, lx, x); + ix = jx & 0x7fffffff; - /* x is INF or NaN */ - if(ix>=0x7ff00000) { - if (jx>=0) return one/x+one; /* tanh(+-inf)=+-1 */ - else return one/x-one; /* tanh(NaN) = NaN */ - } + /* x is INF or NaN */ + if (ix >= 0x7ff00000) + { + if (jx >= 0) + return one / x + one; /* tanh(+-inf)=+-1 */ + else + return one / x - one; /* tanh(NaN) = NaN */ + } - /* |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 */ - t = __expm1(two*fabs(x)); - z = one - two/(t+two); - } else { - t = __expm1(-two*fabs(x)); - z= -t/(t+two); - } - /* |x| > 22, return +-1 */ - } else { - z = one - tiny; /* raised inexact flag */ + /* |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 */ + { + t = __expm1 (two * fabs (x)); + z = one - two / (t + two); + } + else + { + t = __expm1 (-two * fabs (x)); + z = -t / (t + two); } - return (jx>=0)? z: -z; + /* |x| > 22, return +-1 */ + } + else + { + z = one - tiny; /* raised inexact flag */ + } + return (jx >= 0) ? z : -z; } weak_alias (__tanh, tanh) #ifdef NO_LONG_DOUBLE |