55  *              fl(1.0+2/(expm1(2*threshold)+2)) == 1.
  56  *
  57  * Special cases:
  58  *      tanhl(NaN) is NaN;
  59  *      only tanhl(0.0)=0.0 is exact for finite argument.
  60  */
  61 
  62 #include "libm.h"
  63 #include "longdouble.h"
  64 
  65 static const long double small = 1.0e-20L, one = 1.0, two = 2.0,
  66 #ifndef lint
  67         big = 1.0e+20L,
  68 #endif
  69         threshold = 45.0L;
  70 
  71 long double
  72 tanhl(long double x) {
  73         long double t, y, z;
  74         int signx;

  75 
  76         if (isnanl(x))
  77                 return (x + x);         /* x is NaN */
  78         signx = signbitl(x);
  79         t = fabsl(x);
  80         z = one;
  81         if (t <= threshold) {
  82                 if (t > one)
  83                         z = one - two / (expm1l(t + t) + two);
  84                 else if (t > small) {
  85                         y = expm1l(-t - t);
  86                         z = -y / (y + two);
  87                 } else {
  88 #ifndef lint
  89                         volatile long double dummy = t + big;
  90                                                         /* inexact if t != 0 */
  91 #endif
  92                         return (x);
  93                 }
  94         } else if (!finitel(t))
  95                 return (copysignl(one, x));
  96         else
  97                 return (signx ? -z + small * small : z - small * small);
  98         return (signx ? -z : z);
  99 }

  55  *              fl(1.0+2/(expm1(2*threshold)+2)) == 1.
  56  *
  57  * Special cases:
  58  *      tanhl(NaN) is NaN;
  59  *      only tanhl(0.0)=0.0 is exact for finite argument.
  60  */
  61 
  62 #include "libm.h"
  63 #include "longdouble.h"
  64 
  65 static const long double small = 1.0e-20L, one = 1.0, two = 2.0,
  66 #ifndef lint
  67         big = 1.0e+20L,
  68 #endif
  69         threshold = 45.0L;
  70 
  71 long double
  72 tanhl(long double x) {
  73         long double t, y, z;
  74         int signx;
  75         volatile long double dummy;
  76 
  77         if (isnanl(x))
  78                 return (x + x);         /* x is NaN */
  79         signx = signbitl(x);
  80         t = fabsl(x);
  81         z = one;
  82         if (t <= threshold) {
  83                 if (t > one)
  84                         z = one - two / (expm1l(t + t) + two);
  85                 else if (t > small) {
  86                         y = expm1l(-t - t);
  87                         z = -y / (y + two);
  88                 } else {
  89 #ifndef lint
  90                         dummy = t + big;
  91                                                         /* inexact if t != 0 */
  92 #endif
  93                         return (x);
  94                 }
  95         } else if (!finitel(t))
  96                 return (copysignl(one, x));
  97         else
  98                 return (signx ? -z + small * small : z - small * small);
  99         return (signx ? -z : z);
 100 }