Optimize libm

[thirdparty/glibc.git] / math / w_jn.c

diff --git a/math/w_jn.c b/math/w_jn.c
index 41ec8b32d4ae54c71f17a1060cf4a48421d28052..36fb44816337d1b7328b813f736e73f0a4ea5ebd 100644 (file)
--- a/math/w_jn.c
+++ b/math/w_jn.c
@@ -1,98 +1,63 @@
-/* @(#)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.
- * ====================================================
- */
+/* Copyright (C) 2011 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@gmail.com>, 2011.
 
-#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
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
 
-/*
- * 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.
- *
- */
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
 
+#include <fenv.h>
 #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
+
+/* wrapper jn */
+double
+jn (int n, double x)
 {
-#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
+  if (__builtin_expect (fabs (x) > X_TLOSS, 0) && _LIB_VERSION != _IEEE_)
+    /* jn(n,|x|>X_TLOSS) */
+    return __kernel_standard (n, x, 38);
+
+  return __ieee754_jn (n, x);
 }
 #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
+/* wrapper yn */
+double
+yn (int n, double x)
 {
-#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
+  if (__builtin_expect (x <= 0.0 || x > X_TLOSS, 0) && _LIB_VERSION != _IEEE_)
+    {
+      if (x < 0.0)
+       {
+         /* d = zero/(x-x) */
+         feraiseexcept (FE_INVALID);
+         return __kernel_standard (n, x, 13);
+       }
+      else if (x == 0.0)
+       /* d = -one/(x-x) */
+       return __kernel_standard (n, x, 12);
+      else
+       /* yn(n,x>X_TLOSS) */
+       return __kernel_standard (n, x, 39);
+    }
+
+  return __ieee754_yn (n, x);
 }
 #ifdef NO_LONG_DOUBLE
 strong_alias (yn, ynl)