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66 lines
1.5 KiB
C
66 lines
1.5 KiB
C
/* Base 10 logarithmic function.
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Copyright (C) 2012-2025 Free Software Foundation, Inc.
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This file is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation, either version 3 of the
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License, or (at your option) any later version.
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This file is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>. */
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#include <config.h>
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/* Specification. */
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#include <math.h>
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#if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
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long double
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log10l (long double x)
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{
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return log10 (x);
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}
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#elif 0 /* was: HAVE_LOG10L */
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# include <float.h>
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long double
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log10l (long double x)
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# undef log10l
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{
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/* Work around the OSF/1 5.1 bug. */
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if (x == 0.0L)
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/* Return -Infinity. */
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return -1.0L / 0.0L;
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{
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long double y = log10l (x);
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# ifdef __sgi
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/* Normalize the +Infinity value. */
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if (y > LDBL_MAX)
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y = 1.0L / 0.0L;
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# endif
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return y;
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}
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}
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#else
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/* 1 / log(10) */
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static const long double inv_log10 =
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0.43429448190325182765112891891660508229439700580366656611445378316586464920887L;
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long double
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log10l (long double x)
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{
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return logl (x) * inv_log10;
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}
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#endif
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