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authorUlrich Drepper <drepper@redhat.com>1999-07-14 00:54:57 +0000
committerUlrich Drepper <drepper@redhat.com>1999-07-14 00:54:57 +0000
commitabfbdde177c3a7155070dda1b2cdc8292054cc26 (patch)
treee021306b596381fbf8311d2b7eb294e918ff17c8 /math/w_jn.c
parent86421aa57ecfd70963ae66848bd6a6dd3b8e0fe6 (diff)
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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