sysdeps/generic/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 #ifdef __STDC__
  51         long double jnl(int n, long double x)   /* wrapper jnl */
  52 #else
  53         long double jnl(n,x)                    /* wrapper jnl */
  54         long double x; int n;
  55 #endif
  56 {
  57 #ifdef _IEEE_LIBM
  58         return __ieee754_jnl(n,x);
  59 #else
  60         long double z;
  61         z = __ieee754_jnl(n,x);
  62         if(_LIB_VERSION == _IEEE_ || __isnanl(x) ) return z;
  63         if(fabsl(x)>X_TLOSS) {
  64             return __kernel_standard((double)n,x,238); /* jn(|x|>X_TLOSS,n) */
  65         } else
  66             return z;
  67 #endif
  68 }
  69
  70 #ifdef __STDC__
  71         long double ynl(int n, long double x)   /* wrapper ynl */
  72 #else
  73         long double ynl(n,x)                    /* wrapper ynl */
  74         long double x; int n;
  75 #endif
  76 {
  77 #ifdef _IEEE_LIBM
  78         return __ieee754_ynl(n,x);
  79 #else
  80         long double z;
  81         z = __ieee754_ynl(n,x);
  82         if(_LIB_VERSION == _IEEE_ || __isnanl(x) ) return z;
  83         if(x <= 0.0){
  84                 if(x==0.0)
  85                     /* d= -one/(x-x); */
  86                     return __kernel_standard((double)n,x,212);
  87                 else
  88                     /* d = zero/(x-x); */
  89                     return __kernel_standard((double)n,x,213);
  90         }
  91         if(x>X_TLOSS) {
  92             return __kernel_standard((double)n,x,239); /* yn(x>X_TLOSS,n) */
  93         } else
  94             return z;
  95 #endif
  96 }