/* nag_correg_robustm (g02hac) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 *
 */

#include <ctype.h>
#include <nag.h>
#include <stdio.h>

#define C(I, J) c[(I)*tdc + J]
#define X(I, J) x[(I)*tdx + J]

int main(void) {
  Integer exit_status = 0, i, j, m, max_iter, n, print_iter, tdc, tdx;
  double *c = 0, cpsi, cucv, dchi, *hpsi = 0, *info = 0, *rs = 0, sigma,
         *theta = 0;
  double tol, *wt = 0, *x = 0, *y = 0;
  char nag_enum_arg[40];
  Nag_CovMatrixEst covmat_est;
  Nag_PsiFun psifun;
  Nag_RegType regtype;
  Nag_SigmaEst sigma_est;
  NagError fail;

  INIT_FAIL(fail);

  printf("nag_correg_robustm (g02hac) Example Program Results\n\n");
  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT " %" NAG_IFMT "", &n, &m);
  if (n > 1 && (m >= 1 && m <= n)) {
    if (!(c = NAG_ALLOC(m * m, double)) || !(theta = NAG_ALLOC(m, double)) ||
        !(x = NAG_ALLOC(n * m, double)) || !(y = NAG_ALLOC(n, double)) ||
        !(rs = NAG_ALLOC(n, double)) || !(wt = NAG_ALLOC(n, double)) ||
        !(info = NAG_ALLOC(4, double)) || !(hpsi = NAG_ALLOC(3, double))) {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
    tdc = m;
    tdx = m;
  } else {
    printf("Invalid n or m.\n");
    exit_status = 1;
    return exit_status;
  }
  /* Read in x and y */
  for (i = 0; i < n; i++) {
    for (j = 0; j < m; j++)
      scanf("%lf", &X(i, j));
    scanf("%lf", &y[i]);
  }
  /* Read in control parameters */
  scanf(" %39s", nag_enum_arg);
  /* nag_enum_name_to_value (x04nac).
   * Converts NAG enum member name to value
   */
  regtype = (Nag_RegType)nag_enum_name_to_value(nag_enum_arg);
  scanf(" %39s", nag_enum_arg);
  psifun = (Nag_PsiFun)nag_enum_name_to_value(nag_enum_arg);
  scanf(" %39s", nag_enum_arg);
  sigma_est = (Nag_SigmaEst)nag_enum_name_to_value(nag_enum_arg);

  /* Read in appropriate weight function parameters. */
  if (regtype != Nag_HuberReg) {
    scanf(" %39s %lf", nag_enum_arg, &cucv);
    covmat_est = (Nag_CovMatrixEst)nag_enum_name_to_value(nag_enum_arg);
  }

  if (psifun != Nag_Lsq) {
    if (psifun == Nag_HuberFun)
      scanf("%lf", &cpsi);
    else
      cpsi = 0.0;
    if (psifun == Nag_HampelFun)
      for (j = 0; j < 3; j++)
        scanf("%lf", &hpsi[j]);
    if (sigma_est == Nag_SigmaChi)
      scanf("%lf", &dchi);
  }
  /* Set values of remaining parameters */
  tol = 5e-5;
  max_iter = 50;
  /* Change print_iter to a positive value if monitoring information
   * is required
   */
  print_iter = 1;
  sigma = 1.0e0;
  for (i = 0; i < m; ++i)
    theta[i] = 0.0e0;

  /* nag_correg_robustm (g02hac).
   * Robust regression, standard M-estimates
   */
  fflush(stdout);
  nag_correg_robustm(regtype, psifun, sigma_est, covmat_est, n, m, x, tdx, y,
                     cpsi, hpsi, cucv, dchi, theta, &sigma, c, tdc, rs, wt, tol,
                     max_iter, print_iter, 0, info, &fail);

  if ((fail.code == NE_NOERROR) || (fail.code == NE_THETA_ITER_EXCEEDED) ||
      (fail.code == NE_LSQ_FAIL_CONV) || (fail.code == NE_MAT_SINGULAR) ||
      (fail.code == NE_WT_LSQ_NOT_FULL_RANK) ||
      (fail.code == NE_REG_MAT_SINGULAR) ||
      (fail.code == NE_COV_MAT_FACTOR_ZERO) ||
      (fail.code == NE_VAR_THETA_LEQ_ZERO) ||
      (fail.code == NE_ERR_DOF_LEQ_ZERO) ||
      (fail.code == NE_ESTIM_SIGMA_ZERO)) {
    if (fail.code != NE_NOERROR) {
      printf("Error from nag_correg_robustm (g02hac).\n%s\n", fail.message);
      printf("    Some of the following results may be unreliable\n");
    }
    printf("Sigma = %10.4f\n\n", sigma);
    printf("       Theta      Standard errors\n\n");
    for (j = 0; j < m; ++j)
      printf("%12.4f %13.4f\n", theta[j], C(j, j));
    printf("\n     Weights      Residuals\n\n");
    for (i = 0; i < n; ++i)
      printf("%12.4f %13.4f\n", wt[i], rs[i]);
  } else {
    printf("Error from nag_correg_robustm (g02hac).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

END:
  NAG_FREE(c);
  NAG_FREE(theta);
  NAG_FREE(x);
  NAG_FREE(y);
  NAG_FREE(rs);
  NAG_FREE(wt);
  NAG_FREE(info);
  NAG_FREE(hpsi);

  return exit_status;
}