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authorZack Weinberg <zackw@panix.com>2017-06-08 15:39:03 -0400
committerZack Weinberg <zackw@panix.com>2017-06-08 15:39:03 -0400
commit5046dbb4a7eba5eccfd258f92f4735c9ffc8d069 (patch)
tree4470480d904b65cf14ca524f96f79eca818c3eaf /REORG.TODO/sysdeps/ieee754/dbl-64/e_acosh.c
parent199fc19d3aaaf57944ef036e15904febe877fc93 (diff)
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Prepare for radical source tree reorganization. zack/build-layout-experiment
All top-level files and directories are moved into a temporary storage
directory, REORG.TODO, except for files that will certainly still
exist in their current form at top level when we're done (COPYING,
COPYING.LIB, LICENSES, NEWS, README), all old ChangeLog files (which
are moved to the new directory OldChangeLogs, instead), and the
generated file INSTALL (which is just deleted; in the new order, there
will be no generated files checked into version control).
Diffstat (limited to 'REORG.TODO/sysdeps/ieee754/dbl-64/e_acosh.c')
-rw-r--r--REORG.TODO/sysdeps/ieee754/dbl-64/e_acosh.c69
1 files changed, 69 insertions, 0 deletions
diff --git a/REORG.TODO/sysdeps/ieee754/dbl-64/e_acosh.c b/REORG.TODO/sysdeps/ieee754/dbl-64/e_acosh.c
new file mode 100644
index 0000000000..c1f3590f75
--- /dev/null
+++ b/REORG.TODO/sysdeps/ieee754/dbl-64/e_acosh.c
@@ -0,0 +1,69 @@
+/* @(#)e_acosh.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.
+ * ====================================================
+ */
+
+/* __ieee754_acosh(x)
+ * Method :
+ *	Based on
+ *		acosh(x) = log [ x + sqrt(x*x-1) ]
+ *	we have
+ *		acosh(x) := log(x)+ln2,	if x is large; else
+ *		acosh(x) := log(2x-1/(sqrt(x*x-1)+x)) if x>2; else
+ *		acosh(x) := log1p(t+sqrt(2.0*t+t*t)); where t=x-1.
+ *
+ * Special cases:
+ *	acosh(x) is NaN with signal if x<1.
+ *	acosh(NaN) is NaN without signal.
+ */
+
+#include <math.h>
+#include <math_private.h>
+
+static const double
+  one = 1.0,
+  ln2 = 6.93147180559945286227e-01;    /* 0x3FE62E42, 0xFEFA39EF */
+
+double
+__ieee754_acosh (double x)
+{
+  double t;
+  int32_t hx;
+  u_int32_t lx;
+  EXTRACT_WORDS (hx, lx, x);
+  if (hx < 0x3ff00000)                  /* x < 1 */
+    {
+      return (x - x) / (x - x);
+    }
+  else if (hx >= 0x41b00000)            /* x > 2**28 */
+    {
+      if (hx >= 0x7ff00000)             /* x is inf of NaN */
+	{
+	  return x + x;
+	}
+      else
+	return __ieee754_log (x) + ln2;         /* acosh(huge)=log(2x) */
+    }
+  else if (((hx - 0x3ff00000) | lx) == 0)
+    {
+      return 0.0;                       /* acosh(1) = 0 */
+    }
+  else if (hx > 0x40000000)             /* 2**28 > x > 2 */
+    {
+      t = x * x;
+      return __ieee754_log (2.0 * x - one / (x + __ieee754_sqrt (t - one)));
+    }
+  else                                  /* 1<x<2 */
+    {
+      t = x - one;
+      return __log1p (t + __ieee754_sqrt (2.0 * t + t * t));
+    }
+}
+strong_alias (__ieee754_acosh, __acosh_finite)