tdiv_ui.c

a very popular packet of cryptography tools,it encloses the most common used algorithm and protocols

/* Test file for mpfr_div_ui.

Copyright 1999, 2000, 2001, 2002 Free Software Foundation.

This file is part of the MPFR Library.

The 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 2.1 of the License, or (at your
option) any later version.

The 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 MPFR Library; see the file COPYING.LIB.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
MA 02111-1307, USA. */

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include "gmp.h"
#include "mpfr.h"
#include "mpfr-test.h"

void check _PROTO((double, unsigned long, mp_rnd_t, double)); 
void special _PROTO((void));
void check_inexact _PROTO((void));

void
check (double d, unsigned long u, mp_rnd_t rnd, double e)
{
  mpfr_t x, y;
  double f;

  mpfr_init2(x, 53); mpfr_init2(y, 53);
#ifdef MPFR_HAVE_FESETROUND
  mpfr_set_machine_rnd_mode(rnd);
#endif
  if (e==0.0) e = d / u;
  mpfr_set_d(x, d, rnd); 
  mpfr_div_ui(y, x, u, rnd); 
  f = mpfr_get_d1 (y);
  if (f != e && (!isnan(f) || !isnan(e))) {
    printf("mpfr_div_ui failed for x=%1.20e, u=%lu, rnd=%s\n", d, u,
	   mpfr_print_rnd_mode(rnd));
    printf("expected result is %1.20e, got %1.20e, dif=%d ulp\n",e,f,ulp(e,f));
    exit(1);
  }
  mpfr_clear(x); mpfr_clear(y); 
}

void
special (void)
{
  mpfr_t x, y;
  unsigned xprec, yprec;

  mpfr_init (x);
  mpfr_init (y);

  mpfr_set_prec (x, 32);
  mpfr_set_prec (y, 32);
  mpfr_set_ui (x, 1, GMP_RNDN);
  mpfr_div_ui (y, x, 3, GMP_RNDN);

  mpfr_set_prec (x, 100);
  mpfr_set_prec (y, 100);
  mpfr_random (x);
  mpfr_div_ui (y, x, 123456, GMP_RNDN);
  mpfr_set_ui (x, 0, GMP_RNDN);
  mpfr_div_ui (y, x, 123456789, GMP_RNDN);
  if (mpfr_cmp_ui (y, 0))
    {
      fprintf (stderr, "mpfr_div_ui gives non-zero for 0/ui\n");
      exit (1);
    }

  /* bug found by Norbert Mueller, 21 Aug 2001 */
  mpfr_set_prec (x, 110);
  mpfr_set_prec (y, 60);
  mpfr_set_str_raw (x, "0.110101110011111110011111001110011001110111000000111110001000111011000011E-44");
  mpfr_div_ui (y, x, 17, GMP_RNDN);
  mpfr_set_str_raw (x, "0.11001010100101100011101110000001100001010110101001010011011E-48");
  if (mpfr_cmp (x, y))
    {
      fprintf (stderr, "Error in x/17 for x=1/16!\n");
      fprintf (stderr, "Expected ");
      mpfr_out_str (stderr, 2, 0, x, GMP_RNDN);
      fprintf (stderr, "\nGot      ");
      mpfr_out_str (stderr, 2, 0, y, GMP_RNDN);
      fprintf (stderr, "\n");
      exit (1);
    }

  for (xprec = 53; xprec <= 128; xprec++)
    {
      mpfr_set_prec (x, xprec);
      mpfr_set_str_raw (x, "0.1100100100001111110011111000000011011100001100110111E2");
      for (yprec = 53; yprec <= 128; yprec++)
	{
	  mpfr_set_prec (y, yprec);
	  mpfr_div_ui (y, x, 1, GMP_RNDN);
	  if (mpfr_get_d1 (x) != mpfr_get_d1 (y))
	    {
	      fprintf (stderr, "division by 1.0 fails for xprec=%u, yprec=%u\n", xprec, yprec);
	      printf ("expected "); mpfr_print_binary (x); putchar ('\n');
	      printf ("got      "); mpfr_print_binary (y); putchar ('\n');
	      exit (1);
	    }
	}
    }

  mpfr_clear (x);
  mpfr_clear (y);
}

void
check_inexact (void)
{
  mpfr_t x, y, z;
  mp_prec_t px, py;
  int inexact, cmp;
  unsigned long int u;
  mp_rnd_t rnd;
  
  mpfr_init (x);
  mpfr_init (y);
  mpfr_init (z);

  for (px=2; px<300; px++)
    {
      mpfr_set_prec (x, px);
      mpfr_random (x);
      do { u = LONG_RAND (); } while (u == 0);
      for (py=2; py<300; py++)
	{
	  mpfr_set_prec (y, py);
	  mpfr_set_prec (z, py + mp_bits_per_limb);
	  for (rnd=0; rnd<4; rnd++)
	    {
	      inexact = mpfr_div_ui (y, x, u, rnd);
	      if (mpfr_mul_ui (z, y, u, rnd))
		{
		  fprintf (stderr, "z <- y * u should be exact for u=%lu\n", u);
		  printf ("y="); mpfr_print_binary (y); putchar ('\n');
		  printf ("z="); mpfr_print_binary (z); putchar ('\n');
		  exit (1);
		}
	      cmp = mpfr_cmp (z, x);
	      if (((inexact == 0) && (cmp != 0)) ||
		  ((inexact > 0) && (cmp <= 0)) ||
		  ((inexact < 0) && (cmp >= 0)))
		{
		  fprintf (stderr, "Wrong inexact flag for u=%lu, rnd=%s\n", u,
			   mpfr_print_rnd_mode(rnd));
		  printf ("x="); mpfr_print_binary (x); putchar ('\n');
		  printf ("y="); mpfr_print_binary (y); putchar ('\n');
		  exit (1);
		}
	    }
	}
    }

  mpfr_clear (x);
  mpfr_clear (y);
  mpfr_clear (z);
}

int
main (int argc, char **argv)
{
  mpfr_t x;
#ifdef MPFR_HAVE_FESETROUND
  int i;
  unsigned long u;
  double d;

  mpfr_test_init ();

  SEED_RAND (time(NULL));
  for (i=0;i<1000000;i++)
    {
      do { u = LONG_RAND(); } while (u==0);
      do { d = drand(); } while (ABS(d/u)<2.2e-307);
      check (d, u, LONG_RAND() % 4, 0.0);
    }
#endif

  check_inexact ();

  special ();

  check(1.0, 3, GMP_RNDN, 3.3333333333333331483e-1);
  check(1.0, 3, GMP_RNDZ, 3.3333333333333331483e-1);
  check(1.0, 3, GMP_RNDU, 3.3333333333333337034e-1);
  check(1.0, 3, GMP_RNDD, 3.3333333333333331483e-1);
  check(1.0, 2116118, GMP_RNDN, 4.7256343927890600483e-7);
  check(1.098612288668109782, 5, GMP_RNDN, 0.21972245773362195087);

  mpfr_init2(x, 100);
  mpfr_set_prec(x, 53);
  mpfr_set_ui(x, 3, GMP_RNDD);
  mpfr_log(x, x, GMP_RNDD);
  mpfr_div_ui(x, x, 5, GMP_RNDD);
  if (mpfr_get_d1 (x) != 0.21972245773362189536) {
    fprintf(stderr, "Error in mpfr_div_ui for x=ln(3), u=5\n"); exit(1);
  }
  mpfr_clear(x);

  return 0;
}