/* nag_opt_conj_grad (e04dgc) Example Program
 *
 * Copyright 1991 Numerical Algorithms Group.
 *
 * Mark 2, 1991.
 * Mark 7 revised, 2001.
 *
 */

#include <nag.h>
#include <stdio.h>
#include <math.h>
#include <nag_stdlib.h>
#include <nage04.h>

#ifdef __cplusplus
extern "C" {
#endif
static void objfun(Integer n, double x[], double *objf, double g[],
                   Nag_Comm *comm);
#ifdef __cplusplus
}
#endif

static void ex1(void);
static void ex2(void);

int main(void)
{
  /* Two examples are called, ex1() which uses the
   * default settings to solve the problem and
   * ex2() which solves the same problem with
   * some optional parameters set by the user.
   */


  Vprintf("e04dgc Example Program Results.\n");
  Vscanf(" %*[^\n]"); /* Skip heading in data file */
  ex1();
  ex2();
  return EXIT_SUCCESS;
}

static void objfun(Integer n, double x[], double *objf, double g[],
                   Nag_Comm *comm)
{
  /* Function to evaluate objective function and its 1st derivatives. */

  double ex1, x1, x2;

  ex1 = exp(x[0]);
  x1 = x[0];
  x2 = x[1];

  *objf = ex1*(4*x1*x1 + 2*x2*x2 + 4*x1*x2 + 2*x2 + 1);

  g[0] = 4*ex1*(2*x1 + x2) + *objf;
  g[1] = 2*ex1*(2*x2 + 2*x1 + 1);
}                               /* objfun */


static void ex1(void)
{
  Integer n;
  double objf;
  double x[2], g[2];
  static NagError fail;

  Vprintf("\ne04dgc example 1: no option setting.\n");

  n = 2; /* Number of variables */

  /* Set the initial estimate of the solution. */
  x[0] = -1.0;
  x[1] = 1.0;

  /* Solve the problem. */
  fail.print = TRUE;
  e04dgc(n, objfun, x, &objf, g, E04_DEFAULT, NAGCOMM_NULL, &fail);

  if (fail.code != NE_NOERROR) exit(EXIT_FAILURE);
} /* ex1 */


static void ex2(void)
{
  Integer n;
  double objf;
  double x[2], g[2];
  Boolean print;
  Nag_E04_Opt options;
  static NagError fail;

  Vprintf("\n\ne04dgc example 2: using option setting.\n");

  /* Initialise options structure and read option values from file */
  fail.print = TRUE;
  print = TRUE;
  e04xxc(&options);
  e04xyc("e04dgc", "stdin", &options, print, "stdout", &fail);
  if (fail.code != NE_NOERROR) exit(EXIT_FAILURE);

  n = 2; /* Number of variables */

  /* Set the initial estimate of the solution. */
  x[0] = -1.0;
  x[1] = 1.0;

  /* Solve the problem. */
  e04dgc(n, objfun, x, &objf, g, &options, NAGCOMM_NULL, &fail);

  if (fail.code != NE_NOERROR) exit(EXIT_FAILURE);
} /* ex2 */