0,0 → 1,93 |
/* Copyright (C) 1994 DJ Delorie, see COPYING.DJ for details */ |
/* @(#)w_jn.c 5.1 93/09/24 */ |
/* |
* ==================================================== |
* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
* |
* Developed at SunPro, a Sun Microsystems, Inc. business. |
* Permission to use, copy, modify, and distribute this |
* software is freely granted, provided that this notice |
* is preserved. |
* ==================================================== |
*/ |
|
#if defined(LIBM_SCCS) && !defined(lint) |
static char rcsid[] = "$Id: w_jn.c,v 1.4 1994/08/10 20:34:42 jtc Exp $"; |
#endif |
|
/* |
* 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 "math.h" |
#include "math_private.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 |
} |