/* Copyright 2001 by Stephen L. Moshier <moshier@na-net.ornl.gov>
- This program is free software; you can redistribute it and/or modify
+ This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2, or (at your option)
- any later version.
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program; see the file COPYING.
- If not, write to the Free Software Foundation,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include <math.h>
-/* logll.c
+/* logll.c
*
* Natural logarithm for 128-bit long double precision.
*
ln2b = 1.4286068203094172321214581765680755001344E-6L;
long double
-logl(long double x)
+logl (long double x)
{
long double z, y, w;
- long double u, t;
- unsigned int m;
+ long double t;
int k, e;
/* Check for IEEE special cases. */
+ /* log(NaN) = NaN. */
+ if (isnanl (x))
+ {
+ return x;
+ }
/* log(0) = -infinity. */
if (x == 0.0L)
{
{
return (x - x) / ZERO;
}
- /* log (infinity or NaN) */
- if (x + x == x || x != x)
+ /* log (infinity) */
+ if (x + x == x)
{
return x + x;
}
/* Extract exponent and reduce domain to 0.703125 <= u < 1.40625 */
- x = frexpl(x, &e);
+ x = frexpl (x, &e);
if (x < 0.703125L)
{
x += x;
/* Series expansion of log(1+z). */
w = z * z;
y = ((((((((((((l15 * z
- + l14) * z
- + l13) * z
- + l12) * z
- + l11) * z
- + l10) * z
- + l9) * z
- + l8) * z
- + l7) * z
- + l6) * z
- + l5) * z
- + l4) * z
+ + l14) * z
+ + l13) * z
+ + l12) * z
+ + l11) * z
+ + l10) * z
+ + l9) * z
+ + l8) * z
+ + l7) * z
+ + l6) * z
+ + l5) * z
+ + l4) * z
+ l3) * z * w;
y -= 0.5 * w;
y += e * ln2b; /* Base 2 exponent offset times ln(2). */