/* nag_ode_ivp_adams_interp(d02qzc) Example Program
 *
 * Copyright 1991 Numerical Algorithms Group.
 *
 * Mark 2, 1991.
 * Mark 6 revised, 2000.
 * Mark 7 revised, 2001.
 *
 */

#include <nag.h>
#include <stdio.h>
#include <nag_stdlib.h>
#include <nagd02.h>
#include <nagx01.h>

#ifdef __cplusplus
extern "C" {
#endif
static void ftry03(Integer neqf, double x, double y[], double yp[],
                   Nag_User *comm);
#ifdef __cplusplus
}
#endif

#define NEQF 2
#define TSTART 0.0

int main(void)
{
  double atol[NEQF], rtol[NEQF], y[NEQF], ywant[NEQF], ypwant[NEQF];
  Boolean crit, alter_g, vectol, one_step, sophist;
  double t, tinc, tout, tcrit, twant, hmax, pi;
  Integer max_step, i, j, neqf, neqg, nwant;
  Nag_Start state;
  Nag_ODE_Adams opt;
  static NagError fail;

  fail.print = TRUE;

  Vprintf("d02qzc Example Program Results\n");
  pi = X01AAC;
  state = Nag_NewStart;
  neqf = NEQF;
  neqg = 0;
  sophist = FALSE;
  vectol = TRUE;
  for (i = 0; i < 2; ++i)
    {
      atol[i] = 1e-08;
      rtol[i] = 0.0001;
    }
  one_step = TRUE;
  crit = TRUE;
  tinc = pi * 0.0625;
  tcrit = tinc * 8.0;
  tout = tcrit;
  max_step = 500;
  hmax = 2.0;
  t = TSTART;
  twant = TSTART + tinc;
  nwant = 2;
  y[0] = 0.0;
  y[1] = 1.0;
  Vprintf("\n   T        Y(1)    Y(2)\n");
  Vprintf(" %6.4f   %7.4f %7.4f  \n",t, y[0], y[1]);

  d02qwc(&state, neqf, vectol, atol, rtol, one_step, crit,
         tcrit, hmax, max_step, neqg, &alter_g, sophist, &opt, &fail);

  j = 1;

  while (t < tout && fail.code == NE_NOERROR)
    {
      d02qfc(neqf, ftry03, &t, y, tout, NULLDFN, NAGUSER_DEFAULT, &opt, &fail);

      while (twant <= t && fail.code == NE_NOERROR)
        {
          d02qzc(neqf, twant, nwant, ywant, ypwant, &opt, &fail);

          Vprintf(" %6.4f   %7.4f %7.4f  \n",twant, ywant[0], ywant[1]);
          ++j;
          twant = (double)j*tinc + 0.0;
        }
    }
  /* Free the memory which was allocated by
   * d02qwc to the pointers inside opt.
   */
  d02qyc(&opt);

  if (fail.code == NE_NOERROR) return EXIT_SUCCESS;
  else return EXIT_FAILURE;
}


static void ftry03(Integer neqf, double x, double y[], double yp[],
                   Nag_User *comm)
{
  yp[0] = y[1];
  yp[1] = -y[0];
}                               /* ftry03 */