/* nag_step_regsn (g02eec) Example Program.
 *
 * Copyright 2002 Numerical Algorithms Group.
 *
 * Mark 7, 2002.
 */

#include <stdio.h>
#include <string.h>
#include <nag.h>
#include <nagx04.h>
#include <nag_stdlib.h>
#include <nagg02.h>

int main(int argc, char *argv[])
{
  FILE            *fpin, *fpout;
  /* Scalars */
  double          chrss, f, fin, rss;
  Integer         exit_status, i, idf, ifr, istep, j, m, maxip, n, nterm, pdq,
                  pdx;
  /* Arrays */
  char            nag_enum_arg[40];
  char            *newvar;
  double          *exss = 0, *p = 0, *q = 0, *wt = 0, *x = 0, *y = 0;
  double          *wtptr = 0;
  Integer         *sx = 0;
  char            **free_vars, **model;
  const char      *vname[] = { "DAY", "BOD", "TKN", "TS", "TVS", "COD" };
  /* NAG Types */
  Nag_OrderType   order;
  Nag_IncludeMean mean;
  Nag_Boolean     addvar = Nag_FALSE, weight;
  NagError        fail;

#ifdef NAG_COLUMN_MAJOR
#define X(I, J) x[(J-1)*pdx + I - 1]
  order = Nag_ColMajor;
#else
#define X(I, J) x[(I-1)*pdx + J - 1]
  order = Nag_RowMajor;
#endif

  INIT_FAIL(fail);

  /* Check for command-line IO options */
  fpin = nag_example_file_io(argc, argv, "-data", NULL);
  fpout = nag_example_file_io(argc, argv, "-results", NULL);
  exit_status = 0;
  fprintf(fpout, "nag_step_regsn (g02eec) Example Program Results\n");

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");

  fscanf(fpin, "%ld%ld", &n, &m);
  fscanf(fpin, " %s", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  mean = (Nag_IncludeMean) nag_enum_name_to_value(nag_enum_arg);
  fscanf(fpin, " %s", nag_enum_arg);
  weight = (Nag_Boolean) nag_enum_name_to_value(nag_enum_arg);
  maxip = m;

  /* Allocate memory */
  if (!(exss = NAG_ALLOC(maxip, double)) ||
      !(p = NAG_ALLOC(maxip+1, double)) ||
      !(q = NAG_ALLOC(n * (maxip+2), double)) ||
      !(wt = NAG_ALLOC(n, double)) ||
      !(x = NAG_ALLOC(n * m, double)) ||
      !(y = NAG_ALLOC(n, double)) ||
      !(sx = NAG_ALLOC(m, Integer)) ||
      !(free_vars = NAG_ALLOC(maxip, char *)) ||
      !(model = NAG_ALLOC(maxip, char *))
      )
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

#ifdef NAG_COLUMN_MAJOR
  pdx = n;
  pdq = n;
#else
  pdx = m;
  pdq = maxip+2;
#endif

  if (weight)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= m; ++j)
            fscanf(fpin, "%lf", &X(i, j));
          fscanf(fpin, "%lf%lf%*[^\n] ", &y[i - 1], &wt[i - 1]);
          wtptr = wt;
        }
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = 1; j <= m; ++j)
            fscanf(fpin, "%lf", &X(i, j));
          fscanf(fpin, "%lf%*[^\n] ", &y[i - 1]);
        }
    }

  for (j = 1; j <= m; ++j)
    fscanf(fpin, "%ld", &sx[j - 1]);
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%lf%*[^\n] ", &fin);
  fprintf(fpout, "\n");

  istep = 0;
  for (i = 1; i <= m; ++i)
    {
      /* nag_step_regsn (g02eec).
       * Fits a linear regression model by forward selection
       */
      nag_step_regsn(order, &istep, mean, n, m, x, pdx, vname, sx, maxip,
                     y, wtptr, fin, &addvar, &newvar, &chrss, &f, model,
                     &nterm, &rss, &idf, &ifr, free_vars, exss, q, pdq, p,
                     &fail);

      if (fail.code != NE_NOERROR)
        {
          fprintf(fpout, "Error from nag_step_regsn (g02eec).\n%s\n",
                  fail.message);
          exit_status = 1;
          goto END;
        }

      fprintf(fpout, "Step %ld\n", istep);
      if (!addvar)
        {
          fprintf(fpout, "No further variables added maximum F =%7.2f\n", f);
          fprintf(fpout, "Free variables:        ");

          for (j = 1; j <= ifr; ++j)
            fprintf(fpout, "%3.3s %s", free_vars[j-1],
                    j%6 == 0 || j == ifr?"\n":" ");

          fprintf(fpout, "\n");
          fprintf(fpout,
                  "Change in residual sums of squares for free variables:\n");

          fprintf(fpout, "                 ");
          for (j = 1; j <= ifr; ++j)
            {
              fprintf(fpout, "%9.4f", exss[j - 1]);
              fprintf(fpout, "%s", j%6 == 0 || j == ifr?"\n":" ");
            }
          goto END;
        }
      else
        {
          fprintf(fpout, "Added variable is %3s\n", newvar);
          fprintf(fpout, "Change in residual sum of squares =%13.4e\n", chrss);
          fprintf(fpout, "F Statistic = %7.2f\n\n", f);
          fprintf(fpout, "Variables in model: ");

          for (j = 1; j <= nterm; ++j)
            fprintf(fpout, "%3s %s", model[j-1],
                    j%6 == 0 || j == nterm?"\n":" ");
          fprintf(fpout, "Residual sum of squares = %13.4e\n", rss);
          fprintf(fpout, "Degrees of freedom = %ld\n\n", idf);
          if (ifr == 0)
            {
              fprintf(fpout, "No free variables remaining\n");
              goto END;
            }

          fprintf(fpout, "%s%6s", "Free variables:  ", "");
          for (j = 1; j <= ifr; ++j)
            {
              fprintf(fpout, "%3.3s ", free_vars[j-1]);
              fprintf(fpout, j%6 == 0 || j == ifr?"\n":" ");
            }
          fprintf(fpout,
                  "Change in residual sums of squares for free variables:\n");
          fprintf(fpout, "                 ");

          for (j = 1; j <= ifr; ++j)
            fprintf(fpout, "%9.4f%s", exss[j - 1],
                    j%6 == 0 || j == ifr?"\n":" ");
          fprintf(fpout, "\n");
        }
    }

 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (model) NAG_FREE(model);
  if (free_vars) NAG_FREE(free_vars);
  if (exss) NAG_FREE(exss);
  if (p) NAG_FREE(p);
  if (q) NAG_FREE(q);
  if (wt) NAG_FREE(wt);
  if (x) NAG_FREE(x);
  if (y) NAG_FREE(y);
  if (sx) NAG_FREE(sx);

  return exit_status;
}