Fix exp10 inaccuracy and exceptions (bugs 13884, 13914).

1 files changed, 48 insertions, 0 deletions

diff --git a/sysdeps/ieee754/dbl-64/e_exp10.c b/sysdeps/ieee754/dbl-64/e_exp10.c
new file mode 100644
index 0000000..eeb63a6
--- /dev/null
+++ b/sysdeps/ieee754/dbl-64/e_exp10.c
@@ -0,0 +1,48 @@
+/* Copyright (C) 2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <math.h>
+#include <math_private.h>
+#include <float.h>
+
+static const double log10_high = 0x2.4d7637p0;
+static const double log10_low = 0x7.6aaa2b05ba95cp-28;
+
+double
+__ieee754_exp10 (double arg)
+{
+  int32_t lx;
+  double arg_high, arg_low;
+  double exp_high, exp_low;
+
+  if (!__finite (arg))
+    return __ieee754_exp (arg);
+  if (arg < DBL_MIN_10_EXP - DBL_DIG - 10)
+    return DBL_MIN * DBL_MIN;
+  else if (arg > DBL_MAX_10_EXP + 1)
+    return DBL_MAX * DBL_MAX;
+
+  GET_LOW_WORD (lx, arg);
+  lx &= 0xf8000000;
+  arg_high = arg;
+  SET_LOW_WORD (arg_high, lx);
+  arg_low = arg - arg_high;
+  exp_high = arg_high * log10_high;
+  exp_low = arg_high * log10_low + arg_low * M_LN10;
+  return __ieee754_exp (exp_high) * __ieee754_exp (exp_low);
+}
+strong_alias (__ieee754_exp10, __exp10_finite)