#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <mpfr.h>

int main (void)
{
  mpfr_t x[2];
  mpfr_rnd_t r[2] = { MPFR_RNDD, MPFR_RNDU };
  char s[2][32];
  mpfr_exp_t e;
  int i;

  mpfr_inits2 (64, x[0], x[1], (mpfr_ptr) 0);

  for (i = 0; i < 2; i++)
    {
      mpfr_sqrt_ui (x[i], 2, r[i]);
      mpfr_get_str (s[i], &e, 8, 17, x[i], MPFR_RNDZ);
      assert (e == 1);
    }
  assert (strcmp (s[0], s[1]) == 0);
  printf ("sqrt(2) = %c.%s...\n", s[0][0], s[0] + 1);

  for (i = 0; i < 2; i++)
    {
      mpfr_sqrt_ui (x[i], 3, r[i]);
      mpfr_get_str (s[i], &e, 8, 17, x[i], MPFR_RNDZ);
      assert (e == 1);
    }
  assert (strcmp (s[0], s[1]) == 0);
  printf ("sqrt(3) = %c.%s...\n", s[0][0], s[0] + 1);

  for (i = 0; i < 2; i++)
    {
      mpfr_sqrt_ui (x[i], 5, r[i]);
      mpfr_get_str (s[i], &e, 8, 17, x[i], MPFR_RNDZ);
      assert (e == 1);
    }
  assert (strcmp (s[0], s[1]) == 0);
  printf ("sqrt(5) = %c.%s...\n", s[0][0], s[0] + 1);

  for (i = 0; i < 2; i++)
    {
      mpfr_add_ui (x[i], x[i], 1, r[i]);
      mpfr_div_2ui (x[i], x[i], 1, r[i]);
      mpfr_get_str (s[i], &e, 8, 17, x[i], MPFR_RNDZ);
      assert (e == 1);
    }
  assert (strcmp (s[0], s[1]) == 0);
  printf ("phi     = %c.%s...\n", s[0][0], s[0] + 1);

  for (i = 0; i < 2; i++)
    {
      mpfr_const_pi (x[i], r[i]);
      mpfr_get_str (s[i], &e, 8, 17, x[i], MPFR_RNDZ);
      assert (e == 1);
    }
  assert (strcmp (s[0], s[1]) == 0);
  printf ("pi      = %c.%s...\n", s[0][0], s[0] + 1);

  for (i = 0; i < 2; i++)
    {
      mpfr_set_ui (x[i], 1, r[i]);
      mpfr_exp (x[i], x[i], r[i]);
      mpfr_get_str (s[i], &e, 8, 17, x[i], MPFR_RNDZ);
      assert (e == 1);
    }
  assert (strcmp (s[0], s[1]) == 0);
  printf ("e       = %c.%s...\n", s[0][0], s[0] + 1);

  mpfr_clears (x[0], x[1], (mpfr_ptr) 0);

  return 0;
}

/* To check https://en.wikipedia.org/wiki/Octal#Irrational_numbers
 *
 * $Id: octal.c 112045 2018-10-04 22:29:43Z vinc17/zira $
 */