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Diffstat (limited to 'math/w_jn.c')
| -rw-r--r-- | math/w_jn.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/math/w_jn.c b/math/w_jn.c new file mode 100644 index 0000000000..85fc383fb7 --- /dev/null +++ b/math/w_jn.c @@ -0,0 +1,99 @@ +/* @(#)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 |