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annotate lib/sqrtl.c @ 17363:5a51fb7777a9

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sys_select, sys_time: port 2013-01-30 Solaris 2.6 fix to Cygwin Problem reported by Marco Atzeri in <http://lists.gnu.org/archive/html/bug-gnulib/2013-03/msg00000.html>. * lib/sys_select.in.h [HAVE_SYS_SELECT_H && _CYGWIN_SYS_TIME_H]: Simply delegate to the system <sys/select.h> in this case too. Also, pay attention to _GL_SYS_SELECT_H_REDIRECT_FROM_SYS_TIME_H only if OSF/1, since otherwise Cygwin breaks, and it doesn't seem to be needed on Solaris either. * lib/sys_time.in.h [_CYGWIN_SYS_TIME_H]: Simply delgate to the system <sys/time.h> in this case.
author Paul Eggert <eggert@cs.ucla.edu>
date Tue, 19 Mar 2013 09:08:47 -0700
parents e542fd46ad6f
children 344018b6e5d7
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1 /* Emulation for sqrtl.
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2 Contributed by Paolo Bonzini
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3
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4 Copyright 2002-2003, 2007, 2009-2013 Free Software Foundation, Inc.
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5
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6 This file is part of gnulib.
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7
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8 This program is free software: you can redistribute it and/or modify
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9 it under the terms of the GNU General Public License as published by
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10 the Free Software Foundation; either version 3 of the License, or
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11 (at your option) any later version.
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13 This program is distributed in the hope that it will be useful,
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14 but WITHOUT ANY WARRANTY; without even the implied warranty of
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15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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16 GNU General Public License for more details.
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17
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18 You should have received a copy of the GNU General Public License
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19 along with this program. If not, see <http://www.gnu.org/licenses/>. */
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20
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21 #include <config.h>
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22
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23 /* Specification. */
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24 #include <math.h>
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25
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26 #if HAVE_SAME_LONG_DOUBLE_AS_DOUBLE
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27
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28 long double
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29 sqrtl (long double x)
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30 {
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31 return sqrt (x);
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32 }
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33
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34 #else
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35
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36 # include <float.h>
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37
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38 /* A simple Newton-Raphson method. */
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39 long double
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40 sqrtl (long double x)
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41 {
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42 long double delta, y;
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43 int exponent;
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44
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45 /* Check for NaN */
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46 if (isnanl (x))
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47 return x;
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48
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49 /* Check for negative numbers */
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50 if (x < 0.0L)
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51 return (long double) sqrt (-1);
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52
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53 /* Check for zero and infinites */
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54 if (x + x == x)
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55 return x;
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56
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57 frexpl (x, &exponent);
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58 y = ldexpl (x, -exponent / 2);
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59
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60 do
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61 {
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62 delta = y;
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63 y = (y + x / y) * 0.5L;
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64 delta -= y;
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65 }
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66 while (delta != 0.0L);
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67
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68 return y;
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69 }
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70
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71 #endif