git://sourceware.org / glibc.git / blame
| Commit | Line | Data |
|---|---|---|
| f7eac6eb RM |
1 | /* @(#)w_jn.c 5.1 93/09/24 */ |
| 2 | /* | |
| 3 | * ==================================================== | |
| 4 | * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. | |
| 5 | * | |
| 6 | * Developed at SunPro, a Sun Microsystems, Inc. business. | |
| 7 | * Permission to use, copy, modify, and distribute this | |
| 8 | * software is freely granted, provided that this notice | |
| 9 | * is preserved. | |
| 10 | * ==================================================== | |
| 11 | */ | |
| 12 | ||
| 13 | #if defined(LIBM_SCCS) && !defined(lint) | |
| 14 | static char rcsid[] = "$NetBSD: w_jn.c,v 1.6 1995/05/10 20:49:19 jtc Exp $"; | |
| 15 | #endif | |
| 16 | ||
| 17 | /* | |
| 18 | * wrapper jn(int n, double x), yn(int n, double x) | |
| 19 | * floating point Bessel's function of the 1st and 2nd kind | |
| 20 | * of order n | |
| 21 | * | |
| 22 | * Special cases: | |
| 23 | * y0(0)=y1(0)=yn(n,0) = -inf with division by zero signal; | |
| 24 | * y0(-ve)=y1(-ve)=yn(n,-ve) are NaN with invalid signal. | |
| 25 | * Note 2. About jn(n,x), yn(n,x) | |
| 26 | * For n=0, j0(x) is called, | |
| 27 | * for n=1, j1(x) is called, | |
| 28 | * for n<x, forward recursion us used starting | |
| 29 | * from values of j0(x) and j1(x). | |
| 30 | * for n>x, a continued fraction approximation to | |
| 31 | * j(n,x)/j(n-1,x) is evaluated and then backward | |
| 32 | * recursion is used starting from a supposed value | |
| 33 | * for j(n,x). The resulting value of j(0,x) is | |
| 34 | * compared with the actual value to correct the | |
| 35 | * supposed value of j(n,x). | |
| 36 | * | |
| 37 | * yn(n,x) is similar in all respects, except | |
| 38 | * that forward recursion is used for all | |
| 39 | * values of n>1. | |
| 40 | * | |
| 41 | */ | |
| 42 | ||
| 43 | #include "math.h" | |
| 44 | #include "math_private.h" | |
| 45 | ||
| 46 | #ifdef __STDC__ | |
| 47 | double __jn(int n, double x) /* wrapper jn */ | |
| 48 | #else | |
| 49 | double __jn(n,x) /* wrapper jn */ | |
| 50 | double x; int n; | |
| 51 | #endif | |
| 52 | { | |
| 53 | #ifdef _IEEE_LIBM | |
| 54 | return __ieee754_jn(n,x); | |
| 55 | #else | |
| 56 | double z; | |
| 57 | z = __ieee754_jn(n,x); | |
| 58 | if(_LIB_VERSION == _IEEE_ || __isnan(x) ) return z; | |
| 59 | if(fabs(x)>X_TLOSS) { | |
| 60 | return __kernel_standard((double)n,x,38); /* jn(|x|>X_TLOSS,n) */ | |
| 61 | } else | |
| 62 | return z; | |
| 63 | #endif | |
| 64 | } | |
| 65 | weak_alias (__jn, jn) | |
| 66 | ||
| 67 | #ifdef __STDC__ | |
| 68 | double __yn(int n, double x) /* wrapper yn */ | |
| 69 | #else | |
| 70 | double __yn(n,x) /* wrapper yn */ | |
| 71 | double x; int n; | |
| 72 | #endif | |
| 73 | { | |
| 74 | #ifdef _IEEE_LIBM | |
| 75 | return __ieee754_yn(n,x); | |
| 76 | #else | |
| 77 | double z; | |
| 78 | z = __ieee754_yn(n,x); | |
| 79 | if(_LIB_VERSION == _IEEE_ || __isnan(x) ) return z; | |
| 80 | if(x <= 0.0){ | |
| 81 | if(x==0.0) | |
| 82 | /* d= -one/(x-x); */ | |
| 83 | return __kernel_standard((double)n,x,12); | |
| 84 | else | |
| 85 | /* d = zero/(x-x); */ | |
| 86 | return __kernel_standard((double)n,x,13); | |
| 87 | } | |
| 88 | if(x>X_TLOSS) { | |
| 89 | return __kernel_standard((double)n,x,39); /* yn(x>X_TLOSS,n) */ | |
| 90 | } else | |
| 91 | return z; | |
| 92 | #endif | |
| 93 | } | |
| 94 | weak_alias (__yn, yn) |