1 | /* mpf_sqrt -- Compute the square root of a float. |
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2 | |
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3 | Copyright 1993, 1994, 1996, 2000, 2001 Free Software Foundation, Inc. |
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4 | |
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5 | This file is part of the GNU MP Library. |
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6 | |
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7 | The GNU MP Library is free software; you can redistribute it and/or modify |
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8 | it under the terms of the GNU Lesser General Public License as published by |
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9 | the Free Software Foundation; either version 2.1 of the License, or (at your |
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10 | option) any later version. |
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11 | |
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12 | The GNU MP Library is distributed in the hope that it will be useful, but |
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13 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
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14 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
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15 | License for more details. |
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16 | |
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17 | You should have received a copy of the GNU Lesser General Public License |
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18 | along with the GNU MP Library; see the file COPYING.LIB. If not, write to |
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19 | the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
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20 | MA 02111-1307, USA. */ |
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21 | |
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22 | #include <stdio.h> /* for NULL */ |
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23 | #include "gmp.h" |
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24 | #include "gmp-impl.h" |
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25 | |
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26 | void |
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27 | mpf_sqrt (mpf_ptr r, mpf_srcptr u) |
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28 | { |
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29 | mp_size_t usize; |
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30 | mp_ptr up, tp; |
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31 | mp_size_t prec; |
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32 | mp_exp_t tsize, rexp; |
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33 | TMP_DECL (marker); |
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34 | |
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35 | usize = u->_mp_size; |
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36 | if (usize <= 0) |
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37 | { |
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38 | if (usize < 0) |
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39 | SQRT_OF_NEGATIVE; |
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40 | r->_mp_size = 0; |
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41 | r->_mp_exp = 0; |
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42 | return; |
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43 | } |
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44 | |
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45 | TMP_MARK (marker); |
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46 | |
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47 | prec = r->_mp_prec; |
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48 | rexp = (u->_mp_exp + 1) >> 1; /* round towards -inf */ |
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49 | tsize = 2 * prec + (u->_mp_exp & 1); |
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50 | |
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51 | up = u->_mp_d; |
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52 | tp = (mp_ptr) TMP_ALLOC (tsize * BYTES_PER_MP_LIMB); |
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53 | |
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54 | if (usize > tsize) |
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55 | { |
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56 | up += usize - tsize; |
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57 | usize = tsize; |
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58 | MPN_COPY (tp, up, tsize); |
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59 | } |
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60 | else |
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61 | { |
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62 | MPN_ZERO (tp, tsize - usize); |
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63 | MPN_COPY (tp + (tsize - usize), up, usize); |
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64 | } |
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65 | |
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66 | mpn_sqrtrem (r->_mp_d, NULL, tp, tsize); |
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67 | |
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68 | r->_mp_size = (tsize + 1) / 2; |
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69 | r->_mp_exp = rexp; |
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70 | TMP_FREE (marker); |
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71 | } |
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