Skip to content
This repository
branch: v1_8_7_72-mbari
Fetching contributors…

Octocat-spinner-32-eaf2f5

Cannot retrieve contributors at this time

file 89 lines (77 sloc) 1.79 kb
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88
/**********************************************************************

acosh.c -

$Author$
$Date$
created at: Fri Apr 12 00:34:17 JST 2002

public domain rewrite of acosh(3), asinh(3) and atanh(3)

**********************************************************************/

#include <errno.h>
#include <float.h>
#include <math.h>

/* DBL_MANT_DIG must be less than 4 times of bits of int */
#ifndef DBL_MANT_DIG
#define DBL_MANT_DIG 53 /* in this case, at least 12 digit precision */
#endif
#define BIG_CRITERIA_BIT (1<<DBL_MANT_DIG/2)
#if BIG_CRITERIA_BIT > 0
#define BIG_CRITERIA (1.0*BIG_CRITERIA_BIT)
#else
#define BIG_CRITERIA (1.0*(1<<DBL_MANT_DIG/4)*(1<<(DBL_MANT_DIG/2+1-DBL_MANT_DIG/4)))
#endif
#define SMALL_CRITERIA_BIT (1<<(DBL_MANT_DIG/3))
#if SMALL_CRITERIA_BIT > 0
#define SMALL_CRITERIA (1.0/SMALL_CRITERIA_BIT)
#else
#define SMALL_CRITERIA (1.0*(1<<DBL_MANT_DIG/4)*(1<<(DBL_MANT_DIG/3+1-DBL_MANT_DIG/4)))
#endif

#ifndef HAVE_ACOSH
double
acosh(x)
    double x;
{
    if (x < 1)
x = -1; /* NaN */
    else if (x == 1)
return 0;
    else if (x > BIG_CRITERIA)
x += x;
    else
x += sqrt((x + 1) * (x - 1));
    return log(x);
}
#endif

#ifndef HAVE_ASINH
double
asinh(x)
    double x;
{
    int neg = x < 0;
    double z = fabs(x);

    if (z < SMALL_CRITERIA) return x;
    if (z < (1.0/(1<<DBL_MANT_DIG/5))) {
double x2 = z * z;
z *= 1 + x2 * (-1.0/6.0 + x2 * 3.0/40.0);
    }
    else if (z > BIG_CRITERIA) {
z = log(z + z);
    }
    else {
z = log(z + sqrt(z * z + 1));
    }
    if (neg) z = -z;
    return z;
}
#endif

#ifndef HAVE_ATANH
double
atanh(x)
    double x;
{
    int neg = x < 0;
    double z = fabs(x);

    if (z < SMALL_CRITERIA) return x;
    z = log(z > 1 ? -1 : (1 + z) / (1 - z)) / 2;
    if (neg) z = -z;
    return z;
}
#endif
Something went wrong with that request. Please try again.