Subversion Repositories planix.SVN

Rev

Rev 2 | Details | Compare with Previous | Last modification | View Log | RSS feed

Rev Author Line No. Line
2 - 1 
#include <u.h>
2 
#include <libc.h>
3 
 
4 
/*
5 
 * sinh(arg) returns the hyperbolic sine of its floating-
6 
 * point argument.
7 
 *
8 
 * The exponential function is called for arguments
9 
 * greater in magnitude than 0.5.
10 
 *
11 
 * A series is used for arguments smaller in magnitude than 0.5.
12 
 * The coefficients are #2029 from Hart & Cheney. (20.36D)
13 
 *
14 
 * cosh(arg) is computed from the exponential function for
15 
 * all arguments.
16 
 */
17 
 
18 
static	double	p0  = -0.6307673640497716991184787251e+6;
19 
static	double	p1  = -0.8991272022039509355398013511e+5;
20 
static	double	p2  = -0.2894211355989563807284660366e+4;
21 
static	double	p3  = -0.2630563213397497062819489e+2;
22 
static	double	q0  = -0.6307673640497716991212077277e+6;
23 
static	double	q1   = 0.1521517378790019070696485176e+5;
24 
static	double	q2  = -0.173678953558233699533450911e+3;
25 
 
26 
double
27 
sinh(double arg)
28 
{
29 
	double temp, argsq;
30 
	int sign;
31 
 
32 
	sign = 0;
33 
	if(arg < 0) {
34 
		arg = -arg;
35 
		sign++;
36 
	}
37 
	if(arg > 21) {
38 
		temp = exp(arg)/2;
39 
		goto out;
40 
	}
41 
	if(arg > 0.5) {
42 
		temp = (exp(arg) - exp(-arg))/2;
43 
		goto out;
44 
	}
45 
	argsq = arg*arg;
46 
	temp = (((p3*argsq+p2)*argsq+p1)*argsq+p0)*arg;
47 
	temp /= (((argsq+q2)*argsq+q1)*argsq+q0);
48 
out:
49 
	if(sign)
50 
		temp = -temp;
51 
	return temp;
52 
}
53 
 
54 
double
55 
cosh(double arg)
56 
{
57 
	if(arg < 0)
58 
		arg = - arg;
59 
	if(arg > 21)
60 
		return exp(arg)/2;
61 
	return (exp(arg) + exp(-arg))/2;
62 
}