95 lines
1.5 KiB
C
95 lines
1.5 KiB
C
/*
|
|
* (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
|
|
* See the copyright notice in the ACK home directory, in the file "Copyright".
|
|
*
|
|
* Author: Ceriel J.H. Jacobs
|
|
*/
|
|
/* $Id$ */
|
|
|
|
#include <math.h>
|
|
#include <float.h>
|
|
#include <errno.h>
|
|
#include <ack/config.h>
|
|
#include "localmath.h"
|
|
|
|
#if ACKCONF_WANT_FLOAT
|
|
|
|
static double
|
|
sinh_cosh(double x, int cosh_flag)
|
|
{
|
|
/* Algorithm and coefficients from:
|
|
"Software manual for the elementary functions"
|
|
by W.J. Cody and W. Waite, Prentice-Hall, 1980
|
|
*/
|
|
|
|
static double p[] = {
|
|
-0.35181283430177117881e+6,
|
|
-0.11563521196851768270e+5,
|
|
-0.16375798202630751372e+3,
|
|
-0.78966127417357099479e+0
|
|
};
|
|
static double q[] = {
|
|
-0.21108770058106271242e+7,
|
|
0.36162723109421836460e+5,
|
|
-0.27773523119650701167e+3,
|
|
1.0
|
|
};
|
|
int negative = x < 0;
|
|
double y = negative ? -x : x;
|
|
|
|
if (__IsNan(x))
|
|
{
|
|
errno = EDOM;
|
|
return x;
|
|
}
|
|
if (!cosh_flag && y <= 1.0)
|
|
{
|
|
/* ??? check for underflow ??? */
|
|
y = y * y;
|
|
return x + x * y * POLYNOM3(y, p) / POLYNOM3(y, q);
|
|
}
|
|
|
|
if (y >= M_LN_MAX_D)
|
|
{
|
|
/* exp(y) would cause overflow */
|
|
#define LNV 0.69316101074218750000e+0
|
|
#define VD2M1 0.52820835025874852469e-4
|
|
double w = y - LNV;
|
|
|
|
if (w < M_LN_MAX_D + M_LN2 - LNV)
|
|
{
|
|
x = exp(w);
|
|
x += VD2M1 * x;
|
|
}
|
|
else
|
|
{
|
|
errno = ERANGE;
|
|
x = HUGE_VAL;
|
|
}
|
|
}
|
|
else
|
|
{
|
|
double z = exp(y);
|
|
|
|
x = 0.5 * (z + (cosh_flag ? 1.0 : -1.0) / z);
|
|
}
|
|
return negative ? -x : x;
|
|
}
|
|
|
|
double
|
|
sinh(double x)
|
|
{
|
|
return sinh_cosh(x, 0);
|
|
}
|
|
|
|
double
|
|
cosh(double x)
|
|
{
|
|
if (x < 0)
|
|
x = -x;
|
|
return sinh_cosh(x, 1);
|
|
}
|
|
|
|
#endif
|
|
|