From be5524ae411e0e3165eef05142f65055f16a9837 Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Fri, 12 Apr 2002 03:24:52 +0000
Subject: /tmp/log

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@2368 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 missing/acosh.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 missing/acosh.c

(limited to 'missing/acosh.c')

diff --git a/missing/acosh.c b/missing/acosh.c
new file mode 100644
index 0000000000..6a9daffa5f
--- /dev/null
+++ b/missing/acosh.c
@@ -0,0 +1,88 @@
+/**********************************************************************
+
+  acosh.c -
+
+  $Author$
+  $Date$
+  created at: Fri Apr 12 00:34:17 JST 2002
+
+  public domain rewrite of acosh(3), asinh(3) and atanh(3)
+
+**********************************************************************/
+
+#include <errno.h>
+#include <float.h>
+#include <math.h>
+
+/* DBL_MANT_DIG must be less than 4 times of bits of int */
+#ifdef DBL_MANT_DIG
+#define DBL_MANT_DIG 53		/* in this case, at least 12 digit precision */
+#endif
+#define BIG_CRITERIA_BIT (1<<DBL_MANT_DIG/2)
+#if BIG_CRITERIA_BIT > 0
+#define BIG_CRITERIA (1.0*BIG_CRITERIA_BIT)
+#else
+#define BIG_CRITERIA (1.0*(1<<DBL_MANT_DIG/4)*(1<<(DBL_MANT_DIG/2+1-DBL_MANT_DIG/4)))
+#endif
+#define SMALL_CRITERIA_BIT (1<<(DBL_MANT_DIG/3))
+#if SMALL_CRITERIA_BIT > 0
+#define SMALL_CRITERIA (1.0/SMALL_CRITERIA_BIT)
+#else
+#define SMALL_CRITERIA (1.0*(1<<DBL_MANT_DIG/4)*(1<<(DBL_MANT_DIG/3+1-DBL_MANT_DIG/4)))
+#endif
+
+#ifndef HAVE_ACOSH
+double
+acosh(x)
+    double x;
+{
+    if (x < 1)
+	x = -1;			/* NaN */
+    else if (x == 1)
+	return 0;
+    else if (x > BIG_CRITERIA)
+	x += x;
+    else
+	x += sqrt((x + 1) * (x - 1));
+    return log(x);
+}
+#endif
+
+#ifndef HAVE_ASINH
+double
+asinh(x)
+    double x;
+{
+    int neg = x < 0;
+    double z = fabs(x);
+
+    if (z < SMALL_CRITERIA) return x;
+    if (z < (1.0/(1<<DBL_MANT_DIG/5))) {
+	double x2 = z * z;
+	z *= 1 + x2 * (-1.0/6.0 + x2 * 3.0/40.0);
+    }
+    else if (z > BIG_CRITERIA) {
+	z = log(z + z);
+    }
+    else {
+	z = log(z + sqrt(z * z + 1));
+    }
+    if (neg) z = -z;
+    return z;
+}
+#endif
+
+#ifndef HAVE_ATANH
+double
+atanh(x)
+    double x;
+{
+    int neg = x < 0;
+    double z = fabs(x);
+
+    if (z < SMALL_CRITERIA) return x;
+    z = log(z > 1 ? -1 : (1 + z) / (1 - z)) / 2;
+    if (neg) z = -z;
+    return z;
+}
+#endif
-- 
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