/* tfmod -- test file for mpfr_fmod

Copyright 2007 Free Software Foundation, Inc.
Contributed by the Arenaire and Cacao projects, INRIA.

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., 51 Franklin St, Fifth Floor, Boston,
MA 02110-1301, USA. */

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

#include "mpfr-test.h"

#define TEST_FUNCTION mpfr_fmod
#define TWO_ARGS
#include "tgeneric.c"

/* compute remainder as in definition:
   r = x - n * y, where n = trunc(x/y).
   warning: may change flags. */
static int
slow_fmod (mpfr_ptr r, mpfr_srcptr x, mpfr_srcptr y, mp_rnd_t rnd)
{
  mpfr_t q;
  int inexact;
  if (MPFR_UNLIKELY (MPFR_IS_SINGULAR (x) || MPFR_IS_SINGULAR (y)))
    {
      if (MPFR_IS_NAN (x) || MPFR_IS_NAN (y) || MPFR_IS_INF (x)
	  || MPFR_IS_ZERO (y))
	{
	  MPFR_SET_NAN (r);
	  MPFR_RET_NAN;
	}
      else			/* either y is Inf and x is 0 or non-special,
				   or x is 0 and y is non-special,
				   in both cases the quotient is zero. */
	return mpfr_set (r, x, rnd);
    }
  /* regular cases */
  /* if 2^(ex-1) <= |x| < 2^ex, and 2^(ey-1) <= |y| < 2^ey,
     then |x/y| < 2^(ex-ey+1) */
  mpfr_init2 (q,
	      MAX (MPFR_PREC_MIN, mpfr_get_exp (x) - mpfr_get_exp (y) + 1));
  mpfr_div (q, x, y, GMP_RNDZ);
  mpfr_trunc (q, q);                            /* may change inexact flag */
  mpfr_prec_round (q, mpfr_get_prec (q) + mpfr_get_prec (y), GMP_RNDZ);
  inexact = mpfr_mul (q, q, y, GMP_RNDZ);	/* exact */
  inexact = mpfr_sub (r, x, q, rnd);
  mpfr_clear (q);
  return inexact;
}

static void
test_failed (mpfr_t erem, mpfr_t grem, mpfr_t x, mpfr_t y, mp_rnd_t rnd)
{
  fprintf (stderr, "error : mpfr_fmod (r, x, y, rnd)\n  x = ");
  mpfr_out_str (stderr, 10, 0, x, GMP_RNDD);
  fprintf (stderr, "\n  y = ");
  mpfr_out_str (stderr, 10, 0, y, GMP_RNDD);
  fprintf (stderr, "\nrnd = %s\n", mpfr_print_rnd_mode (rnd));
  fprintf (stderr, "\n  expected r = ");
  mpfr_out_str (stderr, 10, 0, erem, GMP_RNDD);
  fprintf (stderr, "\n  got      r = ");
  mpfr_out_str (stderr, 10, 0, grem, GMP_RNDD);
  fprintf (stderr, "\n");

  mpfr_clears (erem, grem, x, y, (void *) 0);
  exit (1);
}

static void
check (mpfr_t r0, mpfr_t x, mpfr_t y, mp_rnd_t rnd)
{
  int inex0, inex1;
  mpfr_t r1;
  mpfr_init2 (r1, mpfr_get_prec (r0));

  inex0 = mpfr_fmod (r0, x, y, rnd);
  inex1 = slow_fmod (r1, x, y, rnd);
  if (!mpfr_equal_p (r0, r1))
    test_failed (r1, r0, x, y, rnd);
  MPFR_ASSERTN (inex0 == inex1);
  mpfr_clear (r1);
}

static void 
special (void)
{
  int inexact;
  mpfr_t x, y, r;
  mpfr_inits (x, y, r, (void *)0);

  /* NaN mod NaN is NaN */
  mpfr_set_nan (x);
  mpfr_set_nan (y);
  inexact = mpfr_fmod (r, x, y, GMP_RNDN);
  if (!mpfr_nan_p (r))
    test_failed (r, x, x, y, GMP_RNDN);
  if (inexact)
    {
      fprintf (stderr, "error : mpfr_fmod (NaN, NaN) should be exact\n");
      goto error;
    } 

  /* NaN mod +0 is NaN */
  mpfr_set_ui (y, 0, GMP_RNDN);
  inexact = mpfr_fmod (r, x, y, GMP_RNDN);
  if (!mpfr_nan_p (r))
    test_failed (r, x, x, y, GMP_RNDN);
  if (inexact)
    {
      fprintf (stderr, "error : mpfr_fmod (NaN, +0) should be exact\n");
      goto error;
    } 
  
  /* 3.1415 mod +0 is NaN */
  mpfr_set_d (x, 3.1415, GMP_RNDN);
  inexact = mpfr_fmod (r, x, y, GMP_RNDN);
  if (!mpfr_nan_p (r))
    test_failed (r, x, x, y, GMP_RNDN);
  if (inexact)
    {
      fprintf (stderr, "error : mpfr_fmod (3.1415, NaN) should be exact\n");
      goto error;
    } 

  /* 3.1415 mod +Inf is 3.1415 */
  mpfr_set_inf (y, 1);
  inexact = mpfr_fmod (r, x, y, GMP_RNDN);
  if (MPFR_IS_SINGULAR (r))
    test_failed (r, x, x, y, GMP_RNDN);
  if (inexact)
    {
      fprintf (stderr, "error : mpfr_fmod (3.1415, +Inf) should be exact\n");
      goto error;
    } 
  
  mpfr_clears (x, y, r, (void *)0);
  return;

 error:
  mpfr_clears (x, y, r, (void *)0);
  exit (1);
  
  
}

int
main (int argc, char *argv[])
{
  mpfr_t x, y, r;

  tests_start_mpfr ();
  mpfr_inits (x, y, r, (void *)0);

  test_generic (2, 100, 100);

  special ();

  /* remainder = 0 */
  mpfr_set_str (y, "FEDCBA987654321p-64", 16, GMP_RNDN);
  mpfr_pow_ui (x, y, 42, GMP_RNDN);
  check (r, x, y, GMP_RNDN);

  /* x < y */
  mpfr_mul_d (x, y, .12345, GMP_RNDN);
  check (r, x, y, GMP_RNDN);

  /* sign(x) = sign (r) */
  mpfr_set_str (x, "123798", 10, GMP_RNDN);
  mpfr_set_str (y, "10", 10, GMP_RNDN);
  check (r, x, y, GMP_RNDN);

  /* huge difference between precisions */
  mpfr_set_prec (x, 314);
  mpfr_const_pi (x, GMP_RNDD); /* x = pi */
  mpfr_set_prec (y, 8);
  mpfr_set_ui (y, 1, GMP_RNDD);
  mpfr_div_2ui (y, y, 3, GMP_RNDD); /* y = 1/8 */
  mpfr_set_prec (r, 123); 
  check (r, x, y, GMP_RNDD);
  mpfr_clears (x, y, r, (void *)0);

  tests_end_mpfr ();
  return 0;
}