tests/mpq/t-get_d.c

/* Test mpq_get_d and mpq_set_d

Copyright 1991, 1993, 1994, 1996, 2000-2003, 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 https://www.gnu.org/licenses/.  */

#include <stdio.h>
#include <stdlib.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);
}