/* exp.c - math routines *//* Copyright 1992-1993 Wind River Systems, Inc. *//*modification history--------------------01e,05feb93,jdi  doc changes based on kdl review.01d,02dec92,jdi  doc tweaks.01c,28oct92,jdi  documentation cleanup.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 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 *//* lnhuge =  9.4961163736712506989E1     , Hex  2^  7   *  .BDEC1DA73E9010 *//* lntiny = -9.5654310917272452386E1     , Hex  2^  7   * -.BF4F01D72E33AF *//* invln2 =  1.4426950408889634148E0     ; Hex  2^  1   *  .B8AA3B295C17F1 *//* p1     =  1.6666666666666602251E-1    , Hex  2^-2    *  .AAAAAAAAAAA9F1 *//* p2     = -2.7777777777015591216E-3    , Hex  2^-8    * -.B60B60B5F5EC94 *//* p3     =  6.6137563214379341918E-5    , Hex  2^-13   *  .8AB355792EF15F *//* p4     = -1.6533902205465250480E-6    , Hex  2^-19   * -.DDEA0E2E935F84 *//* p5     =  4.1381367970572387085E-8    , Hex  2^-24   *  .B1BB4B95F52683 */static long     ln2hix[] = { _0x(7217,4031), _0x(0000,f7d0)};static long     ln2lox[] = { _0x(bcd5,2ce7), _0x(d9cc,e4f1)};static long    lnhugex[] = { _0x(ec1d,43bd), _0x(9010,a73e)};static long    lntinyx[] = { _0x(4f01,c3bf), _0x(33af,d72e)};static long    invln2x[] = { _0x(aa3b,40b8), _0x(17f1,295c)};static long        p1x[] = { _0x(aaaa,3f2a), _0x(a9f1,aaaa)};static long        p2x[] = { _0x(0b60,bc36), _0x(ec94,b5f5)};static long        p3x[] = { _0x(b355,398a), _0x(f15f,792e)};static long        p4x[] = { _0x(ea0e,b6dd), _0x(5f84,2e93)};static long        p5x[] = { _0x(bb4b,3431), _0x(2683,95f5)};#define    ln2hi    (*(double*)ln2hix)#define    ln2lo    (*(double*)ln2lox)#define   lnhuge    (*(double*)lnhugex)#define   lntiny    (*(double*)lntinyx)#define   invln2    (*(double*)invln2x)#define       p1    (*(double*)p1x)#define       p2    (*(double*)p2x)#define       p3    (*(double*)p3x)#define       p4    (*(double*)p4x)#define       p5    (*(double*)p5x)#else	/* defined(vax)||defined(tahoe) */static doublep1     =  1.6666666666666601904E-1    , /*Hex  2^-3    *  1.555555555553E */p2     = -2.7777777777015593384E-3    , /*Hex  2^-9    * -1.6C16C16BEBD93 */p3     =  6.6137563214379343612E-5    , /*Hex  2^-14   *  1.1566AAF25DE2C */p4     = -1.6533902205465251539E-6    , /*Hex  2^-20   * -1.BBD41C5D26BF1 */p5     =  4.1381367970572384604E-8    , /*Hex  2^-25   *  1.6376972BEA4D0 */ln2hi  =  6.9314718036912381649E-1    , /*Hex  2^ -1   *  1.62E42FEE00000 */ln2lo  =  1.9082149292705877000E-10   , /*Hex  2^-33   *  1.A39EF35793C76 */lnhuge =  7.1602103751842355450E2     , /*Hex  2^  9   *  1.6602B15B7ECF2 */lntiny = -7.5137154372698068983E2     , /*Hex  2^  9   * -1.77AF8EBEAE354 */invln2 =  1.4426950408889633870E0     ; /*Hex  2^  0   *  1.71547652B82FE */#endif	/* defined(vax)||defined(tahoe) *//******************************************************************************* exp - compute an exponential value (ANSI)** This routine returns the exponential value of <x> in* double precision (IEEE double, 53 bits).** A range error occurs if <x> is too large.** INTERNAL:* Method:* (1) Argument Reduction: given the input <x>, find <r> and integer <k>*     such that:**         x = k*ln2 + r,  |r| <= 0.5*ln2* *     <r> will be represented as r := z+c for better accuracy.* * (2) Compute exp(r) by**         exp(r) = 1 + r + r*R1/(2-R1)**     where:**         R1 = x - x^2*(p1+x^2*(p2+x^2*(p3+x^2*(p4+p5*x^2))))** (3)     exp(x) = 2^k * exp(r)** INCLUDE FILES: math.h** RETURNS: The double-precision exponential value of <x>.** Special cases:*     If <x> is +INF or NaN, exp() returns <x>.*     If <x> is -INF, it returns 0.** SEE ALSO: mathALib** INTERNAL:* Coded in C by K.C. Ng, 1/19/85;* Revised by K.C. Ng on 2/6/85, 2/15/85, 3/7/85, 3/24/85, 4/16/85, 6/14/86.*/double exp    (    double x	/* exponent */    )    {	double scalb(), copysign(), z,hi,lo,c;	int k,finite();#if !defined(vax)&&!defined(tahoe)	if(x!=x) return(x);	/* x is NaN */#endif	/* !defined(vax)&&!defined(tahoe) */	if( x <= lnhuge ) {		if( x >= lntiny ) {		    /* argument reduction : x --> x - k*ln2 */			k=invln2*x+copysign(0.5,x);	/* k=NINT(x/ln2) */		    /* express x-k*ln2 as hi-lo and let x=hi-lo rounded */			hi=x-k*ln2hi;			x=hi-(lo=k*ln2lo);		    /* return 2^k*[1+x+x*c/(2+c)]  */			z=x*x;			c= x - z*(p1+z*(p2+z*(p3+z*(p4+z*p5))));			return  scalb(1.0+(hi-(lo-(x*c)/(2.0-c))),k);		}		/* end of x > lntiny */		else		     /* exp(-big#) underflows to zero */		     if(finite(x))  return(scalb(1.0,-5000));		     /* exp(-INF) is zero */		     else return(0.0);	}	/* end of x < lnhuge */	else	/* exp(INF) is INF, exp(+big#) overflows to INF */	    return( finite(x) ?  scalb(1.0,5000)  : x);    }