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/* Example illustrating how to use mpfr_can_round. */ |
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|
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/* |
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Copyright 2016-2020 Free Software Foundation, Inc. |
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Contributed by the AriC and Caramba projects, INRIA. |
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|
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This file is part of the GNU MPFR Library. |
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|
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The GNU MPFR Library 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 published by |
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the Free Software Foundation; either version 3 of the License, or (at your |
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option) any later version. |
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|
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The GNU MPFR Library is distributed in the hope that it will be useful, but |
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
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License for more details. |
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|
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You should have received a copy of the GNU Lesser General Public License |
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along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see |
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https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc., |
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51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. |
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*/ |
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|
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#include <stdio.h> |
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#include <mpfr.h> |
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|
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int |
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main (void) |
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{ |
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mpfr_t x, y; |
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mpfr_prec_t px = 53, py = 50; |
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mpfr_rnd_t r1, r2; |
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int ok; |
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|
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/* Given an approximation of Pi to px bits computed with rounding mode r1, |
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we call mpfr_can_round() to see if we can deduced the correct rounding |
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of Pi to py bits with rounding mode r2. |
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The error is at most 1 = 2^0 ulp. This translates into err = prec(x). */ |
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mpfr_init2 (x, px); |
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mpfr_init2 (y, py); |
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for (r1 = 0; r1 < 4; r1++) |
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{ |
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mpfr_const_pi (x, r1); |
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printf ("r1=%s approx=", mpfr_print_rnd_mode (r1)); |
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mpfr_out_str (stdout, 2, 0, x, MPFR_RNDN); |
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printf ("\n"); |
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for (r2 = 0; r2 < 4; r2++) |
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{ |
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ok = mpfr_can_round (x, mpfr_get_prec (x), r1, r2, py); |
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printf ("r2=%s ok=%d", mpfr_print_rnd_mode (r2), ok); |
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if (ok) |
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{ |
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mpfr_set (y, x, r2); |
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printf (" "); |
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mpfr_out_str (stdout, 2, 0, y, MPFR_RNDN); |
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} |
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printf ("\n"); |
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} |
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} |
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mpfr_clear (x); |
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mpfr_clear (y); |
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mpfr_free_cache (); |
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return 0; |
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} |
