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[glibc/history.git] / math / w_jnl.c
blob4bb4d6b620a636eef80156a798ff20eeeb7302b0
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 */
6 /*
7 * ====================================================
8 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
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 * ====================================================
17 #if defined(LIBM_SCCS) && !defined(lint)
18 static char rcsid[] = "$NetBSD: $";
19 #endif
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
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).
41 * yn(n,x) is similar in all respects, except
42 * that forward recursion is used for all
43 * values of n>1.
47 #include <math.h>
48 #include "math_private.h"
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
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
69 weak_alias (__jnl, jnl)
71 #ifdef __STDC__
72 long double __ynl(int n, long double x) /* wrapper ynl */
73 #else
74 long double __ynl(n,x) /* wrapper ynl */
75 long double x; int n;
76 #endif
78 #ifdef _IEEE_LIBM
79 return __ieee754_ynl(n,x);
80 #else
81 long double z;
82 z = __ieee754_ynl(n,x);
83 if(_LIB_VERSION == _IEEE_ || __isnanl(x) ) return z;
84 if(x <= 0.0){
85 if(x==0.0)
86 /* d= -one/(x-x); */
87 return __kernel_standard((double)n,x,212);
88 else
89 /* d = zero/(x-x); */
90 return __kernel_standard((double)n,x,213);
92 if(x>X_TLOSS) {
93 return __kernel_standard((double)n,x,239); /* yn(x>X_TLOSS,n) */
94 } else
95 return z;
96 #endif
98 weak_alias (__ynl, ynl)