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88 lines
2.4 KiB
88 lines
2.4 KiB
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/* @(#)w_jn.c 1.3 95/01/18 */ |
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/* |
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* ==================================================== |
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* Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. |
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* |
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* Developed at SunSoft, a Sun Microsystems, Inc. business. |
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* Permission to use, copy, modify, and distribute this |
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* software is freely granted, provided that this notice |
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* is preserved. |
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* ==================================================== |
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*/ |
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/* |
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* wrapper ieee_jn(int n, double x), ieee_yn(int n, double x) |
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* floating point Bessel's function of the 1st and 2nd kind |
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* of order n |
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* |
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* Special cases: |
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* y0(0)=ieee_y1(0)=ieee_yn(n,0) = -inf with division by zero signal; |
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* y0(-ve)=ieee_y1(-ve)=ieee_yn(n,-ve) are NaN with invalid signal. |
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* Note 2. About ieee_jn(n,x), ieee_yn(n,x) |
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* For n=0, ieee_j0(x) is called, |
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* for n=1, ieee_j1(x) is called, |
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* for n<x, forward recursion us used starting |
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* from values of ieee_j0(x) and ieee_j1(x). |
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* for n>x, a continued fraction approximation to |
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* j(n,x)/j(n-1,x) is evaluated and then backward |
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* recursion is used starting from a supposed value |
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* for j(n,x). The resulting value of j(0,x) is |
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* compared with the actual value to correct the |
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* supposed value of j(n,x). |
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* |
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* yn(n,x) is similar in all respects, except |
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* that forward recursion is used for all |
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* values of n>1. |
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* |
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*/ |
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#include "fdlibm.h" |
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#ifdef __STDC__ |
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double ieee_jn(int n, double x) /* wrapper jn */ |
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#else |
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double ieee_jn(n,x) /* wrapper jn */ |
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double x; int n; |
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#endif |
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{ |
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#ifdef _IEEE_LIBM |
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return __ieee754_jn(n,x); |
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#else |
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double z; |
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z = __ieee754_jn(n,x); |
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if(_LIB_VERSION == _IEEE_ || ieee_isnan(x) ) return z; |
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if(ieee_fabs(x)>X_TLOSS) { |
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return __kernel_standard((double)n,x,38); /* ieee_jn(|x|>X_TLOSS,n) */ |
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} else |
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return z; |
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#endif |
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} |
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#ifdef __STDC__ |
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double ieee_yn(int n, double x) /* wrapper yn */ |
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#else |
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double ieee_yn(n,x) /* wrapper yn */ |
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double x; int n; |
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#endif |
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{ |
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#ifdef _IEEE_LIBM |
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return __ieee754_yn(n,x); |
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#else |
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double z; |
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z = __ieee754_yn(n,x); |
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if(_LIB_VERSION == _IEEE_ || ieee_isnan(x) ) return z; |
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if(x <= 0.0){ |
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if(x==0.0) |
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/* d= -one/(x-x); */ |
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return __kernel_standard((double)n,x,12); |
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else |
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/* d = zero/(x-x); */ |
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return __kernel_standard((double)n,x,13); |
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} |
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if(x>X_TLOSS) { |
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return __kernel_standard((double)n,x,39); /* ieee_yn(x>X_TLOSS,n) */ |
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} else |
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return z; |
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#endif |
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}
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