X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Flogl.c;h=16053cf3f3fcea3212c79bd16592c87cb3a3e066;hb=dd6ceef65e424d30db8706273f88c20b015012ce;hp=9048e455a7e1b987079a915e173c10d78a5a82f5;hpb=5657b2536d242966c41c268b9ab4fe8df727bb13;p=gnulib.git diff --git a/lib/logl.c b/lib/logl.c index 9048e455a..16053cf3f 100644 --- a/lib/logl.c +++ b/lib/logl.c @@ -1,3 +1,25 @@ +/* Copyright 2001 by Stephen L. Moshier + + 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. + + This program 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 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. */ + +#include + +/* Specification. */ +#include + /* logll.c * * Natural logarithm for 128-bit long double precision. @@ -42,11 +64,7 @@ * */ -#include - -#include "mathl.h" - -/* Copyright 2001 by Stephen L. Moshier */ +#include "isnanl.h" /* log(1+x) = x - .5 x^2 + x^3 l(x) -.0078125 <= x <= +.0078125 @@ -173,23 +191,33 @@ static const long double long double logl(long double x) { - long double z, y, w, u, t; + long double z, y, w; + long double u, t; unsigned int m; int k, e; /* Check for IEEE special cases. */ + /* log(NaN) = NaN. */ + if (isnanl (x)) + { + return x; + } /* log(0) = -infinity. */ if (x == 0.0L) - return -0.5L / 0.0L; - + { + return -0.5L / ZERO; + } /* log ( x < 0 ) = NaN */ if (x < 0.0L) - return (x - x) / (x - x); - - /* log (infinity or NaN) */ - if (x + x == x || x != x) - return x + x; + { + return (x - x) / ZERO; + } + /* log (infinity) */ + if (x + x == x) + { + return x + x; + } /* Extract exponent and reduce domain to 0.703125 <= u < 1.40625 */ x = frexpl(x, &e); @@ -202,13 +230,13 @@ logl(long double x) /* On this interval the table is not used due to cancellation error. */ if ((x <= 1.0078125L) && (x >= 0.9921875L)) { + z = x - 1.0L; k = 64; t = 1.0L; - z = x - 1.0L; } else { - k = floorl((x - 0.5L) * 128.0L); + k = floorl ((x - 0.5L) * 128.0L); t = 0.5L + k / 128.0L; z = (x - t) / t; }