tests/mpq/t-get_d.c

/* Test mpq_get_d and mpq_set_d

Copyright 1991, 1993, 1994, 1996, 2000, 2001, 2002, 2003, 2012, 2013 Free
Software Foundation, Inc.

This file is part of the GNU MP Library test suite.

The GNU MP Library test suite is free software; you can redistribute it
and/or modify it under the terms of the GNU 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 MP Library test suite 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 General
Public License for more details.

You should have received a copy of the GNU General Public License along with
the GNU MP Library test suite.  If not, see http://www.gnu.org/licenses/.  */

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

#include "gmp.h"
#include "gmp-impl.h"
#include "tests.h"

#ifndef SIZE
#define SIZE 8
#endif

/* VAX D floats only have an 8 bit signed exponent, so anything 2^128 or
   bigger will overflow, that being 4 limbs. */
#if defined (__vax) || defined (__vax__) && SIZE > 4
#undef SIZE
#define SIZE 4
#define EPSIZE 3
#else
#define EPSIZE SIZE
#endif

void dump (mpq_t);

void
check_monotonic (int argc, char **argv)
{
  mpq_t a;
  mp_size_t size;
  int reps = 100;
  int i, j;
  double last_d, new_d;
  mpq_t qlast_d, qnew_d;
  mpq_t eps;

  if (argc == 2)
     reps = atoi (argv[1]);

  /* The idea here is to test the monotonousness of mpq_get_d by adding
     numbers to the numerator and denominator.  */

  mpq_init (a);
  mpq_init (eps);
  mpq_init (qlast_d);
  mpq_init (qnew_d);

  for (i = 0; i < reps; i++)
    {
      size = urandom () % SIZE - SIZE/2;
      mpz_random2 (mpq_numref (a), size);
      do
	{
	  size = urandom () % SIZE - SIZE/2;
	  mpz_random2 (mpq_denref (a), size);
	}
      while (mpz_cmp_ui (mpq_denref (a), 0) == 0);

      mpq_canonicalize (a);

      last_d = mpq_get_d (a);
      mpq_set_d (qlast_d, last_d);
      for (j = 0; j < 10; j++)
	{
	  size = urandom () % EPSIZE + 1;
	  mpz_random2 (mpq_numref (eps), size);
	  size = urandom () % EPSIZE + 1;
	  mpz_random2 (mpq_denref (eps), size);
	  mpq_canonicalize (eps);

	  mpq_add (a, a, eps);
	  mpq_canonicalize (a);
	  new_d = mpq_get_d (a);
	  if (last_d > new_d)
	    {
	      printf ("\nERROR (test %d/%d): bad mpq_get_d results\n", i, j);
	      printf ("last: %.16g\n", last_d);
	      printf (" new: %.16g\n", new_d); dump (a);
	      abort ();
	    }
	  mpq_set_d (qnew_d, new_d);
	  MPQ_CHECK_FORMAT (qnew_d);
	  if (mpq_cmp (qlast_d, qnew_d) > 0)
	    {
	      printf ("ERROR (test %d/%d): bad mpq_set_d results\n", i, j);
	      printf ("last: %.16g\n", last_d); dump (qlast_d);
	      printf (" new: %.16g\n", new_d); dump (qnew_d);
	      abort ();
	    }
	  last_d = new_d;
	  mpq_set (qlast_d, qnew_d);
	}
    }

  mpq_clear (a);
  mpq_clear (eps);
  mpq_clear (qlast_d);
  mpq_clear (qnew_d);
}

double
my_ldexp (double d, int e)
{
  for (;;)
    {
      if (e > 0)
	{
	  if (e >= 16)
	    {
	      d *= 65536.0;
	      e -= 16;
	    }
	  else
	    {
	      d *= 2.0;
	      e -= 1;
	    }
	}
      else if (e < 0)
	{

	  if (e <= -16)
	    {
	      d /= 65536.0;
	      e += 16;
	    }
	  else
	    {
	      d /= 2.0;
	      e += 1;
	    }
	}
      else
	return d;
    }
}

#define MAXEXP 500

#if defined (__vax) || defined (__vax__)
#undef MAXEXP
#define MAXEXP 30
#endif

void
check_random (int argc, char **argv)
{
  gmp_randstate_ptr rands = RANDS;

  double d;
  mpq_t q;
  mpz_t a, t;
  int exp;

  int test, reps = 100000;

  if (argc == 2)
     reps = 100 * atoi (argv[1]);

  mpq_init (q);
  mpz_init (a);
  mpz_init (t);

  for (test = 0; test < reps; test++)
    {
      mpz_rrandomb (a, rands, 53);
      mpz_urandomb (t, rands, 32);
      exp = mpz_get_ui (t) % (2*MAXEXP) - MAXEXP;

      d = my_ldexp (mpz_get_d (a), exp);
      mpq_set_d (q, d);
      /* Check that n/d = a * 2^exp, or
	 d*a 2^{exp} = n */
      mpz_mul (t, a, mpq_denref (q));
      if (exp > 0)
	mpz_mul_2exp (t, t, exp);
      else
	{
	  if (!mpz_divisible_2exp_p (t, -exp))
	    goto fail;
	  mpz_div_2exp (t, t, -exp);
	}
      if (mpz_cmp (t, mpq_numref (q)) != 0)
	{
	fail:
	  printf ("ERROR (check_random test %d): bad mpq_set_d results\n", test);
	  printf ("%.16g\n", d);
	  gmp_printf ("%Qd\n", q);
	  abort ();
	}
    }
  mpq_clear (q);
  mpz_clear (t);
  mpz_clear (a);
}

void
dump (mpq_t x)
{
  mpz_out_str (stdout, 10, mpq_numref (x));
  printf ("/");
  mpz_out_str (stdout, 10, mpq_denref (x));
  printf ("\n");
}

/* Check various values 2^n and 1/2^n. */
void
check_onebit (void)
{
  static const long data[] = {
    -3*GMP_NUMB_BITS-1, -3*GMP_NUMB_BITS, -3*GMP_NUMB_BITS+1,
    -2*GMP_NUMB_BITS-1, -2*GMP_NUMB_BITS, -2*GMP_NUMB_BITS+1,
    -GMP_NUMB_BITS-1, -GMP_NUMB_BITS, -GMP_NUMB_BITS+1,
    -5, -2, -1, 0, 1, 2, 5,
    GMP_NUMB_BITS-1, GMP_NUMB_BITS, GMP_NUMB_BITS+1,
    2*GMP_NUMB_BITS-1, 2*GMP_NUMB_BITS, 2*GMP_NUMB_BITS+1,
    3*GMP_NUMB_BITS-1, 3*GMP_NUMB_BITS, 3*GMP_NUMB_BITS+1,
  };

  int     i, neg;
  long    exp, l;
  mpq_t   q;
  double  got, want;

  mpq_init (q);

  for (i = 0; i < numberof (data); i++)
    {
      exp = data[i];

      mpq_set_ui (q, 1L, 1L);
      if (exp >= 0)
	mpq_mul_2exp (q, q, exp);
      else
	mpq_div_2exp (q, q, -exp);

      want = 1.0;
      for (l = 0; l < exp; l++)
	want *= 2.0;
      for (l = 0; l > exp; l--)
	want /= 2.0;

      for (neg = 0; neg <= 1; neg++)
	{
	  if (neg)
	    {
	      mpq_neg (q, q);
	      want = -want;
	    }

	  got = mpq_get_d (q);

	  if (got != want)
	    {
	      printf    ("mpq_get_d wrong on %s2**%ld\n", neg ? "-" : "", exp);
	      mpq_trace ("   q    ", q);
	      d_trace   ("   want ", want);
	      d_trace   ("   got  ", got);
	      abort();
	    }
	}
    }
  mpq_clear (q);
}

int
main (int argc, char **argv)
{
  tests_start ();

  check_onebit ();
  check_monotonic (argc, argv);
  check_random (argc, argv);

  tests_end ();
  exit (0);
}