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/* @(#)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 ieee_jn(int n, double x), ieee_yn(int n, double x)
* floating point Bessel's function of the 1st and 2nd kind
* of order n
*
* Special cases:
* y0(0)=ieee_y1(0)=ieee_yn(n,0) = -inf with division by zero signal;
* y0(-ve)=ieee_y1(-ve)=ieee_yn(n,-ve) are NaN with invalid signal.
* Note 2. About ieee_jn(n,x), ieee_yn(n,x)
* For n=0, ieee_j0(x) is called,
* for n=1, ieee_j1(x) is called,
* for n<x, forward recursion us used starting
* from values of ieee_j0(x) and ieee_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 ieee_jn(int n, double x) /* wrapper jn */
#else
double ieee_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_ || ieee_isnan(x) ) return z;
if(ieee_fabs(x)>X_TLOSS) {
return __kernel_standard((double)n,x,38); /* ieee_jn(|x|>X_TLOSS,n) */
} else
return z;
#endif
}
#ifdef __STDC__
double ieee_yn(int n, double x) /* wrapper yn */
#else
double ieee_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_ || 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); /* ieee_yn(x>X_TLOSS,n) */
} else
return z;
#endif
}
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