libc/stdio/_scanf.c: heed lots of warnings about signed/unsigned chars
[uclibc-ng.git] / libm / s_asinh.c
blobefdee84a699e0d5ee0c61203f41b7612932b2558
1 /* @(#)s_asinh.c 5.1 93/09/24 */
2 /*
3 * ====================================================
4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
6 * Developed at SunPro, a Sun Microsystems, Inc. business.
7 * Permission to use, copy, modify, and distribute this
8 * software is freely granted, provided that this notice
9 * is preserved.
10 * ====================================================
13 #if defined(LIBM_SCCS) && !defined(lint)
14 static char rcsid[] = "$NetBSD: s_asinh.c,v 1.9 1995/05/12 04:57:37 jtc Exp $";
15 #endif
17 /* asinh(x)
18 * Method :
19 * Based on
20 * asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]
21 * we have
22 * asinh(x) := x if 1+x*x=1,
23 * := sign(x)*(log(x)+ln2)) for large |x|, else
24 * := sign(x)*log(2|x|+1/(|x|+sqrt(x*x+1))) if|x|>2, else
25 * := sign(x)*log1p(|x| + x^2/(1 + sqrt(1+x^2)))
28 #include "math.h"
29 #include "math_private.h"
32 #ifdef __STDC__
33 static const double
34 #else
35 static double
36 #endif
37 one = 1.00000000000000000000e+00, /* 0x3FF00000, 0x00000000 */
38 ln2 = 6.93147180559945286227e-01, /* 0x3FE62E42, 0xFEFA39EF */
39 huge= 1.00000000000000000000e+300;
41 #ifdef __STDC__
42 double asinh(double x)
43 #else
44 double asinh(x)
45 double x;
46 #endif
48 double t,w;
49 int32_t hx,ix;
50 GET_HIGH_WORD(hx,x);
51 ix = hx&0x7fffffff;
52 if(ix>=0x7ff00000) return x+x; /* x is inf or NaN */
53 if(ix< 0x3e300000) { /* |x|<2**-28 */
54 if(huge+x>one) return x; /* return x inexact except 0 */
56 if(ix>0x41b00000) { /* |x| > 2**28 */
57 w = __ieee754_log(fabs(x))+ln2;
58 } else if (ix>0x40000000) { /* 2**28 > |x| > 2.0 */
59 t = fabs(x);
60 w = __ieee754_log(2.0*t+one/(__ieee754_sqrt(x*x+one)+t));
61 } else { /* 2.0 > |x| > 2**-28 */
62 t = x*x;
63 w =log1p(fabs(x)+t/(one+__ieee754_sqrt(one+t)));
65 if(hx>0) return w; else return -w;
67 libm_hidden_def(asinh)