math/w_jnl.c

   1 /* w_jnl.c -- long double version of w_jn.c.
   2  * Conversion to long double by Ulrich Drepper,
   3  * Cygnus Support, drepper@cygnus.com.
   4  */
   5
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  */
  16
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 static char rcsid[] = "$NetBSD: $";
  19 #endif
  20
  21 /*
  22  * wrapper jn(int n, double x), yn(int n, double x)
  23  * floating point Bessel's function of the 1st and 2nd kind
  24  * of order n
  25  *
  26  * Special cases:
  27  *      y0(0)=y1(0)=yn(n,0) = -inf with division by zero signal;
  28  *      y0(-ve)=y1(-ve)=yn(n,-ve) are NaN with invalid signal.
  29  * Note 2. About jn(n,x), yn(n,x)
  30  *      For n=0, j0(x) is called,
  31  *      for n=1, j1(x) is called,
  32  *      for n<x, forward recursion us used starting
  33  *      from values of j0(x) and j1(x).
  34  *      for n>x, a continued fraction approximation to
  35  *      j(n,x)/j(n-1,x) is evaluated and then backward
  36  *      recursion is used starting from a supposed value
  37  *      for j(n,x). The resulting value of j(0,x) is
  38  *      compared with the actual value to correct the
  39  *      supposed value of j(n,x).
  40  *
  41  *      yn(n,x) is similar in all respects, except
  42  *      that forward recursion is used for all
  43  *      values of n>1.
  44  *
  45  */
  46
  47 #include <math.h>
  48 #include <math_private.h>
  49
  50 long double __jnl(int n, long double x) /* wrapper jnl */
  51 {
  52 #ifdef _IEEE_LIBM
  53         return __ieee754_jnl(n,x);
  54 #else
  55         long double z;
  56         z = __ieee754_jnl(n,x);
  57         if (_LIB_VERSION == _IEEE_
  58             || _LIB_VERSION == _POSIX_
  59             || __isnanl(x))
  60           return z;
  61         if(fabsl(x)>X_TLOSS) {
  62             return __kernel_standard_l((double)n,x,238); /* jn(|x|>X_TLOSS,n) */
  63         } else
  64             return z;
  65 #endif
  66 }
  67 weak_alias (__jnl, jnl)
  68
  69 long double __ynl(int n, long double x) /* wrapper ynl */
  70 {
  71 #ifdef _IEEE_LIBM
  72         return __ieee754_ynl(n,x);
  73 #else
  74         long double z;
  75         z = __ieee754_ynl(n,x);
  76         if(_LIB_VERSION == _IEEE_ || __isnanl(x) ) return z;
  77         if(x <= 0.0){
  78                 if(x==0.0)
  79                     /* d= -one/(x-x); */
  80                     return __kernel_standard_l((double)n,x,212);
  81                 else
  82                     /* d = zero/(x-x); */
  83                     return __kernel_standard_l((double)n,x,213);
  84         }
  85         if(x>X_TLOSS && _LIB_VERSION != _POSIX_) {
  86             return __kernel_standard_l((double)n,x,239); /* yn(x>X_TLOSS,n) */
  87         } else
  88             return z;
  89 #endif
  90 }
  91 weak_alias (__ynl, ynl)