62 lines
2.1 KiB
C
62 lines
2.1 KiB
C
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/* mpfr_get_z -- get a multiple-precision integer from
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a floating-point number
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Copyright 2004, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
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Contributed by the Arenaire and Cacao projects, INRIA.
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This file is part of the GNU MPFR Library.
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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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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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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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http://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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#include "mpfr-impl.h"
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int
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mpfr_get_z (mpz_ptr z, mpfr_srcptr f, mpfr_rnd_t rnd)
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{
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int inex;
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mpfr_t r;
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mpfr_exp_t exp;
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if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (f)))
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{
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if (MPFR_UNLIKELY (MPFR_NOTZERO (f)))
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MPFR_SET_ERANGE ();
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mpz_set_ui (z, 0);
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/* The ternary value is 0 even for infinity. Giving the rounding
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direction in this case would not make much sense anyway, and
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the direction would not necessarily match rnd. */
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return 0;
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}
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exp = MPFR_GET_EXP (f);
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/* if exp <= 0, then |f|<1, thus |o(f)|<=1 */
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MPFR_ASSERTN (exp < 0 || exp <= MPFR_PREC_MAX);
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mpfr_init2 (r, (exp < (mpfr_exp_t) MPFR_PREC_MIN ?
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MPFR_PREC_MIN : (mpfr_prec_t) exp));
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inex = mpfr_rint (r, f, rnd);
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MPFR_ASSERTN (inex != 1 && inex != -1); /* integral part of f is
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representable in r */
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MPFR_ASSERTN (MPFR_IS_FP (r));
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exp = mpfr_get_z_2exp (z, r);
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if (exp >= 0)
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mpz_mul_2exp (z, z, exp);
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else
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mpz_fdiv_q_2exp (z, z, -exp);
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mpfr_clear (r);
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return inex;
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}
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