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authorEric Andersen <andersen@codepoet.org>2001-11-22 14:04:29 +0000
committerEric Andersen <andersen@codepoet.org>2001-11-22 14:04:29 +0000
commit7ce331c01ce6eb7b3f5c715a38a24359da9c6ee2 (patch)
tree3a7e8476e868ae15f4da1b7ce26b2db6f434468c /libm/w_jn.c
parentc117dd5fb183afb1a4790a6f6110d88704be6bf8 (diff)
Totally rework the math library, this time based on the MacOs X
math library (which is itself based on the math lib from FreeBSD). -Erik
Diffstat (limited to 'libm/w_jn.c')
-rw-r--r--libm/w_jn.c92
1 files changed, 92 insertions, 0 deletions
diff --git a/libm/w_jn.c b/libm/w_jn.c
new file mode 100644
index 000000000..20ba79beb
--- /dev/null
+++ b/libm/w_jn.c
@@ -0,0 +1,92 @@
+/* @(#)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 __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
+}