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Annotation of OpenXM_contrib/gmp/mpfr/reldiff.c, Revision 1.1.1.1

1.1       ohara       1: /* mpfr_reldiff -- compute relative difference of two floating-point numbers.
                      2:
                      3: Copyright 2000, 2001 Free Software Foundation, Inc.
                      4:
                      5: This file is part of the MPFR Library.
                      6:
                      7: The MPFR Library is free software; you can redistribute it and/or modify
                      8: it under the terms of the GNU Lesser General Public License as published by
                      9: the Free Software Foundation; either version 2.1 of the License, or (at your
                     10: option) any later version.
                     11:
                     12: The MPFR Library is distributed in the hope that it will be useful, but
                     13: WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
                     14: or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
                     15: License for more details.
                     16:
                     17: You should have received a copy of the GNU Lesser General Public License
                     18: along with the MPFR Library; see the file COPYING.LIB.  If not, write to
                     19: the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
                     20: MA 02111-1307, USA. */
                     21:
                     22: #include <stdio.h>
                     23: #include "gmp.h"
                     24: #include "gmp-impl.h"
                     25: #include "mpfr.h"
                     26: #include "mpfr-impl.h"
                     27:
                     28: /* reldiff(b, c) = abs(b-c)/b */
                     29: void
                     30: mpfr_reldiff (mpfr_ptr a, mpfr_srcptr b, mpfr_srcptr c, mp_rnd_t rnd_mode)
                     31: {
                     32:   mpfr_t b_copy;
                     33:
                     34:   if (MPFR_IS_NAN(b) || MPFR_IS_NAN(c))
                     35:     { MPFR_CLEAR_FLAGS(a); MPFR_SET_NAN(a); return; }
                     36:   if (MPFR_IS_INF(b))
                     37:     {
                     38:       if (MPFR_IS_INF(c) && (MPFR_SIGN(c) == MPFR_SIGN(b)))
                     39:        { MPFR_CLEAR_FLAGS(a); MPFR_SET_ZERO(a); return; }
                     40:       else
                     41:        { MPFR_CLEAR_FLAGS(a); MPFR_SET_NAN(a); return; }
                     42:     }
                     43:
                     44:   if (MPFR_IS_INF(c))
                     45:     {
                     46:       MPFR_SET_SAME_SIGN(a, b);
                     47:       MPFR_CLEAR_FLAGS(a);
                     48:       MPFR_SET_INF(a);
                     49:       return;
                     50:     }
                     51:
                     52:   if (MPFR_IS_ZERO(b)) /* reldiff = abs(c)/c = sign(c) */
                     53:     mpfr_set_ui(a, MPFR_SIGN(c), rnd_mode);
                     54:   else
                     55:     {
                     56:       if (a == b)
                     57:         {
                     58:           mpfr_init2 (b_copy, MPFR_PREC(b));
                     59:           mpfr_set (b_copy, b, GMP_RNDN);
                     60:         }
                     61:
                     62:       mpfr_sub (a, b, c, rnd_mode);
                     63:       mpfr_abs (a, a, rnd_mode); /* for compatibility with MPF */
                     64:       mpfr_div (a, a, (a == b) ? b_copy : b, rnd_mode);
                     65:
                     66:       if (a == b)
                     67:         mpfr_clear (b_copy);
                     68:     }
                     69: }
                     70: