| [1166] | 1 | /* Example illustrating how to use mpfr_can_round. */
|
|---|
| 2 |
|
|---|
| 3 | /*
|
|---|
| 4 | Copyright 2016-2020 Free Software Foundation, Inc.
|
|---|
| 5 | Contributed by the AriC and Caramba projects, INRIA.
|
|---|
| 6 |
|
|---|
| 7 | This file is part of the GNU MPFR Library.
|
|---|
| 8 |
|
|---|
| 9 | The GNU MPFR Library is free software; you can redistribute it and/or modify
|
|---|
| 10 | it under the terms of the GNU Lesser General Public License as published by
|
|---|
| 11 | the Free Software Foundation; either version 3 of the License, or (at your
|
|---|
| 12 | option) any later version.
|
|---|
| 13 |
|
|---|
| 14 | The GNU MPFR Library is distributed in the hope that it will be useful, but
|
|---|
| 15 | WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
|
|---|
| 16 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
|
|---|
| 17 | License for more details.
|
|---|
| 18 |
|
|---|
| 19 | You should have received a copy of the GNU Lesser General Public License
|
|---|
| 20 | along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
|
|---|
| 21 | https://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
|
|---|
| 22 | 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
|
|---|
| 23 | */
|
|---|
| 24 |
|
|---|
| 25 | #include <stdio.h>
|
|---|
| 26 | #include <mpfr.h>
|
|---|
| 27 |
|
|---|
| 28 | int
|
|---|
| 29 | main (void)
|
|---|
| 30 | {
|
|---|
| 31 | mpfr_t x, y;
|
|---|
| 32 | mpfr_prec_t px = 53, py = 50;
|
|---|
| 33 | mpfr_rnd_t r1, r2;
|
|---|
| 34 | int ok;
|
|---|
| 35 |
|
|---|
| 36 | /* Given an approximation of Pi to px bits computed with rounding mode r1,
|
|---|
| 37 | we call mpfr_can_round() to see if we can deduced the correct rounding
|
|---|
| 38 | of Pi to py bits with rounding mode r2.
|
|---|
| 39 | The error is at most 1 = 2^0 ulp. This translates into err = prec(x). */
|
|---|
| 40 | mpfr_init2 (x, px);
|
|---|
| 41 | mpfr_init2 (y, py);
|
|---|
| 42 | for (r1 = 0; r1 < 4; r1++)
|
|---|
| 43 | {
|
|---|
| 44 | mpfr_const_pi (x, r1);
|
|---|
| 45 | printf ("r1=%s approx=", mpfr_print_rnd_mode (r1));
|
|---|
| 46 | mpfr_out_str (stdout, 2, 0, x, MPFR_RNDN);
|
|---|
| 47 | printf ("\n");
|
|---|
| 48 | for (r2 = 0; r2 < 4; r2++)
|
|---|
| 49 | {
|
|---|
| 50 | ok = mpfr_can_round (x, mpfr_get_prec (x), r1, r2, py);
|
|---|
| 51 | printf ("r2=%s ok=%d", mpfr_print_rnd_mode (r2), ok);
|
|---|
| 52 | if (ok)
|
|---|
| 53 | {
|
|---|
| 54 | mpfr_set (y, x, r2);
|
|---|
| 55 | printf (" ");
|
|---|
| 56 | mpfr_out_str (stdout, 2, 0, y, MPFR_RNDN);
|
|---|
| 57 | }
|
|---|
| 58 | printf ("\n");
|
|---|
| 59 | }
|
|---|
| 60 | }
|
|---|
| 61 | mpfr_clear (x);
|
|---|
| 62 | mpfr_clear (y);
|
|---|
| 63 | mpfr_free_cache ();
|
|---|
| 64 | return 0;
|
|---|
| 65 | }
|
|---|
