dist/tests/tui_sub.c

/* Test file for mpfr_ui_sub.

Copyright 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.
Contributed by the Arenaire and Cacao projects, INRIA.

This file is part of the GNU MPFR Library.

The GNU MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.

The GNU MPFR Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public License
along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */

#include <stdio.h>
#include <stdlib.h>
#include <float.h>

#include "mpfr-test.h"

static void
special (void)
{
  mpfr_t x, y, res;
  int inexact;

  mpfr_init (x);
  mpfr_init (y);
  mpfr_init (res);

  mpfr_set_prec (x, 24);
  mpfr_set_prec (y, 24);
  mpfr_set_str_binary (y, "0.111100110001011010111");
  inexact = mpfr_ui_sub (x, 1, y, MPFR_RNDN);
  if (inexact)
    {
      printf ("Wrong inexact flag: got %d, expected 0\n", inexact);
      exit (1);
    }

  mpfr_set_prec (x, 24);
  mpfr_set_prec (y, 24);
  mpfr_set_str_binary (y, "0.111100110001011010111");
  if ((inexact = mpfr_ui_sub (x, 38181761, y, MPFR_RNDN)) >= 0)
    {
      printf ("Wrong inexact flag: got %d, expected -1\n", inexact);
      exit (1);
    }

  mpfr_set_prec (x, 63);
  mpfr_set_prec (y, 63);
  mpfr_set_str_binary (y, "0.111110010010100100110101101010001001100101110001000101110111111E-1");
  if ((inexact = mpfr_ui_sub (x, 1541116494, y, MPFR_RNDN)) <= 0)
    {
      printf ("Wrong inexact flag: got %d, expected +1\n", inexact);
      exit (1);
    }

  mpfr_set_prec (x, 32);
  mpfr_set_prec (y, 32);
  mpfr_set_str_binary (y, "0.11011000110111010001011100011100E-1");
  if ((inexact = mpfr_ui_sub (x, 2000375416, y, MPFR_RNDN)) >= 0)
    {
      printf ("Wrong inexact flag: got %d, expected -1\n", inexact);
      exit (1);
    }

  mpfr_set_prec (x, 24);
  mpfr_set_prec (y, 24);
  mpfr_set_str_binary (y, "0.110011011001010011110111E-2");
  if ((inexact = mpfr_ui_sub (x, 927694848, y, MPFR_RNDN)) <= 0)
    {
      printf ("Wrong inexact flag: got %d, expected +1\n", inexact);
      exit (1);
    }

  /* bug found by Mathieu Dutour, 12 Apr 2001 */
  mpfr_set_prec (x, 5);
  mpfr_set_prec (y, 5);
  mpfr_set_prec (res, 5);
  mpfr_set_str_binary (x, "1e-12");

  mpfr_ui_sub (y, 1, x, MPFR_RNDD);
  mpfr_set_str_binary (res, "0.11111");
  if (mpfr_cmp (y, res))
    {
      printf ("Error in mpfr_ui_sub (y, 1, x, MPFR_RNDD) for x=2^(-12)\nexpected 1.1111e-1, got ");
      mpfr_out_str (stdout, 2, 0, y, MPFR_RNDN);
      printf ("\n");
      exit (1);
    }

  mpfr_ui_sub (y, 1, x, MPFR_RNDU);
  mpfr_set_str_binary (res, "1.0");
  if (mpfr_cmp (y, res))
    {
      printf ("Error in mpfr_ui_sub (y, 1, x, MPFR_RNDU) for x=2^(-12)\n"
              "expected 1.0, got ");
      mpfr_out_str (stdout, 2, 0, y, MPFR_RNDN);
      printf ("\n");
      exit (1);
    }

  mpfr_ui_sub (y, 1, x, MPFR_RNDN);
  mpfr_set_str_binary (res, "1.0");
  if (mpfr_cmp (y, res))
    {
      printf ("Error in mpfr_ui_sub (y, 1, x, MPFR_RNDN) for x=2^(-12)\n"
              "expected 1.0, got ");
      mpfr_out_str (stdout, 2, 0, y, MPFR_RNDN);
      printf ("\n");
      exit (1);
    }

  mpfr_set_prec (x, 10);
  mpfr_set_prec (y, 10);
  mpfr_urandomb (x, RANDS);
  mpfr_ui_sub (y, 0, x, MPFR_RNDN);
  if (MPFR_IS_ZERO(x))
    MPFR_ASSERTN(MPFR_IS_ZERO(y));
  else
    MPFR_ASSERTN(mpfr_cmpabs (x, y) == 0 && mpfr_sgn (x) != mpfr_sgn (y));

  mpfr_set_prec (x, 73);
  mpfr_set_str_binary (x, "0.1101111010101011011011100011010000000101110001011111001011011000101111101E-99");
  mpfr_ui_sub (x, 1, x, MPFR_RNDZ);
  mpfr_nextabove (x);
  MPFR_ASSERTN(mpfr_cmp_ui (x, 1) == 0);

  mpfr_clear (x);
  mpfr_clear (y);
  mpfr_clear (res);
}

/* checks that (y-x) gives the right results with 53 bits of precision */
static void
check (unsigned long y, const char *xs, mpfr_rnd_t rnd_mode, const char *zs)
{
  mpfr_t xx, zz;

  mpfr_inits2 (53, xx, zz, (mpfr_ptr) 0);
  mpfr_set_str1 (xx, xs);
  mpfr_ui_sub (zz, y, xx, rnd_mode);
  if (mpfr_cmp_str1 (zz, zs) )
    {
      printf ("expected difference is %s, got\n",zs);
      mpfr_out_str(stdout, 10, 0, zz, MPFR_RNDN);
      printf ("mpfr_ui_sub failed for y=%lu x=%s with rnd_mode=%s\n",
              y, xs, mpfr_print_rnd_mode (rnd_mode));
      exit (1);
    }
  mpfr_clears (xx, zz, (mpfr_ptr) 0);
}

/* if u = o(x-y), v = o(u-x), w = o(v+y), then x-y = u-w */
static void
check_two_sum (mpfr_prec_t p)
{
  unsigned int x;
  mpfr_t y, u, v, w;
  mpfr_rnd_t rnd;
  int inexact;

  mpfr_inits2 (p, y, u, v, w, (mpfr_ptr) 0);
  do
    {
      x = randlimb ();
    }
  while (x < 1);
  mpfr_urandomb (y, RANDS);
  rnd = MPFR_RNDN;
  inexact = mpfr_ui_sub (u, x, y, rnd);
  mpfr_sub_ui (v, u, x, rnd);
  mpfr_add (w, v, y, rnd);
  /* as u = (x-y) + w, we should have inexact and w of same sign */
  if (((inexact == 0) && mpfr_cmp_ui (w, 0)) ||
      ((inexact > 0) && (mpfr_cmp_ui (w, 0) <= 0)) ||
      ((inexact < 0) && (mpfr_cmp_ui (w, 0) >= 0)))
    {
      printf ("Wrong inexact flag for prec=%u, rnd=%s\n",
              (unsigned int) p, mpfr_print_rnd_mode (rnd));
      printf ("x=%u\n", x);
      printf ("y="); mpfr_print_binary(y); puts ("");
      printf ("u="); mpfr_print_binary(u); puts ("");
      printf ("v="); mpfr_print_binary(v); puts ("");
      printf ("w="); mpfr_print_binary(w); puts ("");
      printf ("inexact = %d\n", inexact);
      exit (1);
    }
  mpfr_clears (y, u, v, w, (mpfr_ptr) 0);
}

static void
check_nans (void)
{
  mpfr_t  x, y;

  mpfr_init2 (x, 123L);
  mpfr_init2 (y, 123L);

  /* 1 - nan == nan */
  mpfr_set_nan (x);
  mpfr_ui_sub (y, 1L, x, MPFR_RNDN);
  MPFR_ASSERTN (mpfr_nan_p (y));

  /* 1 - +inf == -inf */
  mpfr_set_inf (x, 1);
  mpfr_ui_sub (y, 1L, x, MPFR_RNDN);
  MPFR_ASSERTN (mpfr_inf_p (y));
  MPFR_ASSERTN (mpfr_sgn (y) < 0);

  /* 1 - -inf == +inf */
  mpfr_set_inf (x, -1);
  mpfr_ui_sub (y, 1L, x, MPFR_RNDN);
  MPFR_ASSERTN (mpfr_inf_p (y));
  MPFR_ASSERTN (mpfr_sgn (y) > 0);

  mpfr_clear (x);
  mpfr_clear (y);
}

/* Check mpfr_ui_sub with u = 0 (unsigned). */
static void check_neg (void)
{
  mpfr_t x, yneg, ysub;
  int i, s;
  int r;

  mpfr_init2 (x, 64);
  mpfr_init2 (yneg, 32);
  mpfr_init2 (ysub, 32);

  for (i = 0; i <= 25; i++)
    {
      mpfr_sqrt_ui (x, i, MPFR_RNDN);
      for (s = 0; s <= 1; s++)
        {
          RND_LOOP (r)
            {
              int tneg, tsub;

              tneg = mpfr_neg (yneg, x, (mpfr_rnd_t) r);
              tsub = mpfr_ui_sub (ysub, 0, x, (mpfr_rnd_t) r);
              MPFR_ASSERTN (mpfr_equal_p (yneg, ysub));
              MPFR_ASSERTN (!(MPFR_IS_POS (yneg) ^ MPFR_IS_POS (ysub)));
              MPFR_ASSERTN (tneg == tsub);
            }
          mpfr_neg (x, x, MPFR_RNDN);
        }
    }

  mpfr_clear (x);
  mpfr_clear (yneg);
  mpfr_clear (ysub);
}

int
main (int argc, char *argv[])
{
  mpfr_prec_t p;
  unsigned k;

  tests_start_mpfr ();

  check_nans ();

  special ();
  for (p=2; p<100; p++)
    for (k=0; k<100; k++)
      check_two_sum (p);

  check(1196426492, "1.4218093058435347e-3", MPFR_RNDN,
        "1.1964264919985781e9");
  check(1092583421, "-1.0880649218158844e9", MPFR_RNDN,
        "2.1806483428158845901e9");
  check(948002822, "1.22191250737771397120e+20", MPFR_RNDN,
        "-1.2219125073682338611e20");
  check(832100416, "4.68311314939691330000e-215", MPFR_RNDD,
        "8.3210041599999988079e8");
  check(1976245324, "1.25296395864546893357e+232", MPFR_RNDZ,
        "-1.2529639586454686577e232");
  check(2128997392, "-1.08496826129284207724e+187", MPFR_RNDU,
        "1.0849682612928422704e187");
  check(293607738, "-1.9967571564050541e-5", MPFR_RNDU,
        "2.9360773800002003e8");
  check(354270183, "2.9469161763489528e3", MPFR_RNDN,
        "3.5426723608382362e8");

  check_neg ();

  tests_end_mpfr ();
  return 0;
}