aboutsummaryrefslogtreecommitdiff
path: root/sysdeps/generic/asinh.c
diff options
context:
space:
mode:
authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/generic/asinh.c
downloadglibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.tar
glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.tar.gz
glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.tar.bz2
glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.zip
initial import
Diffstat (limited to 'sysdeps/generic/asinh.c')
-rw-r--r--sysdeps/generic/asinh.c101
1 files changed, 101 insertions, 0 deletions
diff --git a/sysdeps/generic/asinh.c b/sysdeps/generic/asinh.c
new file mode 100644
index 0000000000..5db8d2ddf7
--- /dev/null
+++ b/sysdeps/generic/asinh.c
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 1985, 1993
+ * The Regents of the University of California. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ * must display the following acknowledgement:
+ * This product includes software developed by the University of
+ * California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef lint
+static char sccsid[] = "@(#)asinh.c 8.1 (Berkeley) 6/4/93";
+#endif /* not lint */
+
+/* ASINH(X)
+ * RETURN THE INVERSE HYPERBOLIC SINE OF X
+ * DOUBLE PRECISION (VAX D format 56 bits, IEEE DOUBLE 53 BITS)
+ * CODED IN C BY K.C. NG, 2/16/85;
+ * REVISED BY K.C. NG on 3/7/85, 3/24/85, 4/16/85.
+ *
+ * Required system supported functions :
+ * copysign(x,y)
+ * sqrt(x)
+ *
+ * Required kernel function:
+ * log1p(x) ...return log(1+x)
+ *
+ * Method :
+ * Based on
+ * asinh(x) = sign(x) * log [ |x| + sqrt(x*x+1) ]
+ * we have
+ * asinh(x) := x if 1+x*x=1,
+ * := sign(x)*(log1p(x)+ln2)) if sqrt(1+x*x)=x, else
+ * := sign(x)*log1p(|x| + |x|/(1/|x| + sqrt(1+(1/|x|)^2)) )
+ *
+ * Accuracy:
+ * asinh(x) returns the exact inverse hyperbolic sine of x nearly rounded.
+ * In a test run with 52,000 random arguments on a VAX, the maximum
+ * observed error was 1.58 ulps (units in the last place).
+ *
+ * Constants:
+ * The hexadecimal values are the intended ones for the following constants.
+ * The decimal values may be used, provided that the compiler will convert
+ * from decimal to binary accurately enough to produce the hexadecimal values
+ * shown.
+ */
+#include "mathimpl.h"
+
+vc(ln2hi, 6.9314718055829871446E-1 ,7217,4031,0000,f7d0, 0, .B17217F7D00000)
+vc(ln2lo, 1.6465949582897081279E-12 ,bcd5,2ce7,d9cc,e4f1, -39, .E7BCD5E4F1D9CC)
+
+ic(ln2hi, 6.9314718036912381649E-1, -1, 1.62E42FEE00000)
+ic(ln2lo, 1.9082149292705877000E-10, -33, 1.A39EF35793C76)
+
+#ifdef vccast
+#define ln2hi vccast(ln2hi)
+#define ln2lo vccast(ln2lo)
+#endif
+
+double asinh(x)
+double x;
+{
+ double t,s;
+ const static double small=1.0E-10, /* fl(1+small*small) == 1 */
+ big =1.0E20, /* fl(1+big) == big */
+ one =1.0 ;
+
+#if !defined(vax)&&!defined(tahoe)
+ if(x!=x) return(x); /* x is NaN */
+#endif /* !defined(vax)&&!defined(tahoe) */
+ if((t=copysign(x,one))>small)
+ if(t<big) {
+ s=one/t; return(copysign(log1p(t+t/(s+sqrt(one+s*s))),x)); }
+ else /* if |x| > big */
+ {s=log1p(t)+ln2lo; return(copysign(s+ln2hi,x));}
+ else /* if |x| < small */
+ return(x);
+}