/* asinh.c - math routines *//* Copyright 1992 Wind River Systems, Inc. *//*modification history--------------------01c,14oct92,jdi  made asinh() nomanual.01b,20sep92,smb  documentation additions01a,08jul92,smb  documentation.*//*DESCRIPTION * Copyright (c) 1985 Regents of the University of California. * All rights reserved. * * Redistribution and use in source and binary forms are permitted * provided that the above copyright notice and this paragraph are * duplicated in all such forms and that any documentation, * advertising materials, and other materials related to such * distribution and use acknowledge that the software was developed * by the University of California, Berkeley.  The name of the * University may not be used to endorse or promote products derived * from this software without specific prior written permission. * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. * * All recipients should regard themselves as participants in an ongoing * research project and hence should feel obligated to report their * experiences (good or bad) with these elementary function codes, using * the sendbug(8) program, to the authors.SEE ALSO: American National Standard X3.159-1989NOMANUAL*/#include "vxWorks.h"#include "math.h"#if defined(vax)||defined(tahoe)	/* VAX/TAHOE D format */#ifdef vax#define _0x(A,B)	0x/**/A/**/B#else	/* vax */#define _0x(A,B)	0x/**/B/**/A#endif	/* vax *//* static double *//* ln2hi  =  6.9314718055829871446E-1    , Hex  2^  0   *  .B17217F7D00000 *//* ln2lo  =  1.6465949582897081279E-12   ; Hex  2^-39   *  .E7BCD5E4F1D9CC */static long     ln2hix[] = { _0x(7217,4031), _0x(0000,f7d0)};static long     ln2lox[] = { _0x(bcd5,2ce7), _0x(d9cc,e4f1)};#define    ln2hi    (*(double*)ln2hix)#define    ln2lo    (*(double*)ln2lox)#else	/* defined(vax)||defined(tahoe) */static doubleln2hi  =  6.9314718036912381649E-1    , /*Hex  2^ -1   *  1.62E42FEE00000 */ln2lo  =  1.9082149292705877000E-10   ; /*Hex  2^-33   *  1.A39EF35793C76 */#endif	/* defined(vax)||defined(tahoe) *//****************************************************************************** asinh	- compute the inverse hyperbolic sine of <x>** ASINH(X)* RETURN THE INVERSE HYPERBOLIC SINE OF X* DOUBLE PRECISION (VAX D format 56 bits, IEEE DOUBLE 53 BITS)* CODED IN C BY K.C. NG, 2/16/85;* REVISED BY K.C. NG on 3/7/85, 3/24/85, 4/16/85.** Required system supported functions are copysign(x,y) and sqrt(x).** Required kernel function is log1p(x) 		...return log(1+x)** Method :* Based on* .CS*    asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]* .CE* we have* .CS*    asinh(x) := x  if  1+x*x=1,*    := sign(x)*(log1p(x)+ln2))	 if sqrt(1+x*x)=x, else*    := sign(x)*log1p(|x| + |x|/(1/|x| + sqrt(1+(1/|x|)^2)) )* .CE** asinh(x) returns the exact inverse hyperbolic sine of x nearly rounded.* In a test run with 52,000 random arguments on a VAX, the maximum* observed error was 1.58 ulps (units in the last place).* The hexadecimal values are the intended ones for the following constants.* The decimal values may be used, provided that the compiler will convert* from decimal to binary accurately enough to produce the hexadecimal values* shown.** NOMANUAL*/double asinh(x)double x;{	double copysign(),log1p(),sqrt(),t,s;	static double small=1.0E-10,	/* fl(1+small*small) == 1 */		      big  =1.0E20,	/* fl(1+big) == big */		      one  =1.0   ;#if !defined(vax)&&!defined(tahoe)	if(x!=x) return(x);	/* x is NaN */#endif	/* !defined(vax)&&!defined(tahoe) */	if((t=copysign(x,one))>small)	    if(t<big) {	     	s=one/t; return(copysign(log1p(t+t/(s+sqrt(one+s*s))),x)); }	    else	/* if |x| > big */		{s=log1p(t)+ln2lo; return(copysign(s+ln2hi,x));}	else	/* if |x| < small */	    return(x);}