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glibc  2.9
Functions | Variables
e_coshf.c File Reference
#include "math.h"
#include "math_private.h"

Go to the source code of this file.

Functions

float __ieee754_coshf (float x)

Variables

static float one = 1.0
static float half = 0.5
static float huge = 1.0e30

Function Documentation

float __ieee754_coshf ( float  x)

Definition at line 33 of file e_coshf.c.

{
       float t,w;
       int32_t ix;

       GET_FLOAT_WORD(ix,x);
       ix &= 0x7fffffff;

    /* x is INF or NaN */
       if(ix>=0x7f800000) return x*x;

    /* |x| in [0,0.5*ln2], return 1+expm1(|x|)^2/(2*exp(|x|)) */
       if(ix<0x3eb17218) {
           t = __expm1f(fabsf(x));
           w = one+t;
           if (ix<0x24000000) return w;   /* cosh(tiny) = 1 */
           return one+(t*t)/(w+w);
       }

    /* |x| in [0.5*ln2,22], return (exp(|x|)+1/exp(|x|)/2; */
       if (ix < 0x41b00000) {
              t = __ieee754_expf(fabsf(x));
              return half*t+half/t;
       }

    /* |x| in [22, log(maxdouble)] return half*exp(|x|) */
       if (ix < 0x42b17180)  return half*__ieee754_expf(fabsf(x));

    /* |x| in [log(maxdouble), overflowthresold] */
       if (ix<=0x42b2d4fc) {
           w = __ieee754_expf(half*fabsf(x));
           t = half*w;
           return t*w;
       }

    /* |x| > overflowthresold, cosh(x) overflow */
       return huge*huge;
}

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Variable Documentation

float half = 0.5 [static]

Definition at line 27 of file e_coshf.c.

float huge = 1.0e30 [static]

Definition at line 27 of file e_coshf.c.

float one = 1.0 [static]

Definition at line 27 of file e_coshf.c.