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glibc/math/w_jn.c
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/* @(#)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[] = "$NetBSD: w_jn.c,v 1.6 1995/05/10 20:49:19 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 NO_LONG_DOUBLE | |
strong_alias (jn, jnl) | |
#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 | |
} | |
#ifdef NO_LONG_DOUBLE | |
strong_alias (yn, ynl) | |
#endif |