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[/] [or1k/] [trunk/] [newlib/] [newlib/] [libm/] [math/] [w_jn.c] - Blame information for rev 1775

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1 39 lampret 
 
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/* @(#)w_jn.c 5.1 93/09/24 */
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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 SunPro, 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 jn(int n, double x), 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)=y1(0)=yn(n,0) = -inf with division by zero signal;
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 *      y0(-ve)=y1(-ve)=yn(n,-ve) are NaN with invalid signal.
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 * Note 2. About jn(n,x), yn(n,x)
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 *      For n=0, j0(x) is called,
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 *      for n=1, j1(x) is called,
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 *      for n<x, forward recursion us used starting
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 *      from values of j0(x) and 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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#include <errno.h>
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#ifndef _DOUBLE_IS_32BITS
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#ifdef __STDC__
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        double jn(int n, double x)      /* wrapper jn */
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#else
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        double 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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        struct exception exc;
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        z = __ieee754_jn(n,x);
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        if(_LIB_VERSION == _IEEE_ || isnan(x) ) return z;
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        if(fabs(x)>X_TLOSS) {
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            /* jn(|x|>X_TLOSS) */
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            exc.type = TLOSS;
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            exc.name = "jn";
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            exc.err = 0;
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            exc.arg1 = n;
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            exc.arg2 = x;
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            exc.retval = 0.0;
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            if (_LIB_VERSION == _POSIX_)
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                errno = ERANGE;
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            else if (!matherr(&exc)) {
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               errno = ERANGE;
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            }
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            if (exc.err != 0)
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               errno = exc.err;
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            return exc.retval;
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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 yn(int n, double x)      /* wrapper yn */
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#else
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        double 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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        struct exception exc;
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        z = __ieee754_yn(n,x);
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        if(_LIB_VERSION == _IEEE_ || isnan(x) ) return z;
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        if(x <= 0.0){
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            /* yn(n,0) = -inf or yn(x<0) = NaN */
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#ifndef HUGE_VAL
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#define HUGE_VAL inf
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            double inf = 0.0;
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            SET_HIGH_WORD(inf,0x7ff00000);      /* set inf to infinite */
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#endif
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            exc.type = DOMAIN;  /* should be SING for IEEE */
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            exc.name = "yn";
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            exc.err = 0;
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            exc.arg1 = n;
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            exc.arg2 = x;
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            if (_LIB_VERSION == _SVID_)
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                exc.retval = -HUGE;
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            else
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                exc.retval = -HUGE_VAL;
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            if (_LIB_VERSION == _POSIX_)
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                errno = EDOM;
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            else if (!matherr(&exc)) {
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                errno = EDOM;
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            }
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            if (exc.err != 0)
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               errno = exc.err;
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            return exc.retval;
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        }
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        if(x>X_TLOSS) {
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            /* yn(x>X_TLOSS) */
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            exc.type = TLOSS;
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            exc.name = "yn";
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            exc.err = 0;
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            exc.arg1 = n;
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            exc.arg2 = x;
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            exc.retval = 0.0;
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            if (_LIB_VERSION == _POSIX_)
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                errno = ERANGE;
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            else if (!matherr(&exc)) {
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                errno = ERANGE;
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            }
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            if (exc.err != 0)
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               errno = exc.err;
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            return exc.retval;
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        } else
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            return z;
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#endif
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}
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#endif /* defined(_DOUBLE_IS_32BITS) */

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