w_jn.c

caffeine-monkey java实现的js模拟引擎

/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 *
 * ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla Communicator client code, released
 * March 31, 1998.
 *
 * The Initial Developer of the Original Code is
 * Sun Microsystems, Inc.
 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

/* @(#)w_jn.c 1.3 95/01/18 */
/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunSoft, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice 
 * is preserved.
 * ====================================================
 */

/*
 * wrapper jn(int n, double x), yn(int n, double x)
 * floating point Bessel's function of the 1st and 2nd kind
 * of order n
 *          
 * Special cases:
 *	y0(0)=y1(0)=yn(n,0) = -inf with division by zero signal;
 *	y0(-ve)=y1(-ve)=yn(n,-ve) are NaN with invalid signal.
 * Note 2. About jn(n,x), yn(n,x)
 *	For n=0, j0(x) is called,
 *	for n=1, j1(x) is called,
 *	for n<x, forward recursion us used starting
 *	from values of j0(x) and j1(x).
 *	for n>x, a continued fraction approximation to
 *	j(n,x)/j(n-1,x) is evaluated and then backward
 *	recursion is used starting from a supposed value
 *	for j(n,x). The resulting value of j(0,x) is
 *	compared with the actual value to correct the
 *	supposed value of j(n,x).
 *
 *	yn(n,x) is similar in all respects, except
 *	that forward recursion is used for all
 *	values of n>1.
 *	
 */

#include "fdlibm.h"

#ifdef __STDC__
	double fd_jn(int n, double x)	/* wrapper jn */
#else
	double fd_jn(n,x)			/* wrapper jn */
	double x; int n;
#endif
{
#ifdef _IEEE_LIBM
	return __ieee754_jn(n,x);
#else
	double z;
	z = __ieee754_jn(n,x);
	if(_LIB_VERSION == _IEEE_ || fd_isnan(x) ) return z;
	if(fd_fabs(x)>X_TLOSS) {
        int err;
	    return __kernel_standard((double)n,x,38,&err); /* jn(|x|>X_TLOSS,n) */
	} else
	    return z;
#endif
}

#ifdef __STDC__
	double yn(int n, double x)	/* wrapper yn */
#else
	double yn(n,x)			/* wrapper yn */
	double x; int n;
#endif
{
#ifdef _IEEE_LIBM
	return __ieee754_yn(n,x);
#else
	double z;
    int err;
	z = __ieee754_yn(n,x);
	if(_LIB_VERSION == _IEEE_ || fd_isnan(x) ) return z;
        if(x <= 0.0){
                if(x==0.0)
                    /* d= -one/(x-x); */
                    return __kernel_standard((double)n,x,12,&err);
                else
                    /* d = zero/(x-x); */
                    return __kernel_standard((double)n,x,13,&err);
        }
	if(x>X_TLOSS) {
	    return __kernel_standard((double)n,x,39,&err); /* yn(x>X_TLOSS,n) */
	} else
	    return z;
#endif
}