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b58ddff026
* merged mpfr 3.0.0 and gmp 5.0.1 in buildtools trunk git-svn-id: file:///srv/svn/repos/haiku/buildtools/trunk@37378 a95241bf-73f2-0310-859d-f6bbb57e9c96
107 lines
3.3 KiB
C
107 lines
3.3 KiB
C
/* generic inverse of a function.
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Copyright 2005, 2006, 2007, 2008, 2009, 2010 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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#define MPFR_NEED_LONGLONG_H
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#include "mpfr-impl.h"
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#ifndef ACTION_SPECIAL
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#define ACTION_SPECIAL
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#endif
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#ifndef ACTION_TINY
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#define ACTION_TINY
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#endif
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/* example of use:
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#define FUNCTION mpfr_sec
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#define INVERSE mpfr_cos
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#define ACTION_NAN(y) do { MPFR_SET_NAN(y); MPFR_RET_NAN; } while (1)
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#define ACTION_INF(y) do { MPFR_SET_NAN(y); MPFR_RET_NAN; } while (1)
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#define ACTION_ZERO(y) return mpfr_set_ui (y, 1, MPFR_RNDN)
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#include "gen_inverse.h"
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*/
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int
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FUNCTION (mpfr_ptr y, mpfr_srcptr x, mpfr_rnd_t rnd_mode)
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{
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mpfr_prec_t precy; /* target precision */
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mpfr_prec_t m; /* working precision */
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mpfr_t z; /* temporary variable to store INVERSE(x) */
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int inexact; /* inexact flag */
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MPFR_ZIV_DECL (loop);
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MPFR_SAVE_EXPO_DECL (expo);
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if (MPFR_UNLIKELY(MPFR_IS_SINGULAR(x)))
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{
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if (MPFR_IS_NAN(x))
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ACTION_NAN(y);
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else if (MPFR_IS_INF(x))
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ACTION_INF(y);
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else /* x = 0 */
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ACTION_ZERO(y,x);
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}
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/* x is neither NaN, Inf nor zero */
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MPFR_SAVE_EXPO_MARK (expo);
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ACTION_TINY (y, x, rnd_mode); /* special case for very small input x */
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precy = MPFR_PREC(y);
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m = precy + MPFR_INT_CEIL_LOG2 (precy) + 3;
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mpfr_init2 (z, m);
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MPFR_ZIV_INIT (loop, m);
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for(;;)
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{
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MPFR_BLOCK_DECL (flags);
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MPFR_BLOCK (flags, INVERSE (z, x, MPFR_RNDZ)); /* error k_u < 1 ulp */
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/* FIXME: the following assumes that if an overflow happens with
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MPFR_EMAX_MAX, then necessarily an underflow happens with
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__gmpfr_emin */
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if (MPFR_OVERFLOW (flags))
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{
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int s = MPFR_SIGN(z);
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MPFR_ZIV_FREE (loop);
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mpfr_clear (z);
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MPFR_SAVE_EXPO_FREE (expo);
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return mpfr_underflow (y, (rnd_mode == MPFR_RNDN) ?
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MPFR_RNDZ : rnd_mode, s);
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}
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mpfr_ui_div (z, 1, z, MPFR_RNDN);
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/* the error is less than c_w + 2*c_u*k_u (see algorithms.tex),
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where c_w = 1/2, c_u = 1 since z was rounded toward zero,
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thus 1/2 + 2 < 4 */
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if (MPFR_LIKELY (MPFR_CAN_ROUND (z, m - 2, precy, rnd_mode)))
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break;
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ACTION_SPECIAL;
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MPFR_ZIV_NEXT (loop, m);
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mpfr_set_prec (z, m);
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}
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MPFR_ZIV_FREE (loop);
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inexact = mpfr_set (y, z, rnd_mode);
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mpfr_clear (z);
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end:
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MPFR_SAVE_EXPO_FREE (expo);
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return mpfr_check_range (y, inexact, rnd_mode);
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}
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