/* @(#)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 jn(int n, double x)	/* wrapper jn */

#else

	double 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_ || isnan(x) ) return z;

	if(fabs(x)>X_TLOSS) {

	    return __kernel_standard((double)n,x,38); /* 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;

	z = __ieee754_yn(n,x);

	if(_LIB_VERSION == _IEEE_ || isnan(x) ) return z;

        if(x <= 0.0){

                if(x==0.0)

                    /* d= -one/(x-x); */

                    return __kernel_standard((double)n,x,12);

                else

                    /* d = zero/(x-x); */

                    return __kernel_standard((double)n,x,13);

        }

	if(x>X_TLOSS) {

	    return __kernel_standard((double)n,x,39); /* yn(x>X_TLOSS,n) */

	} else

	    return z;

#endif

}