/* nag_dgbtrf (f07bdc) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagx04.h>

int main(int argc, char *argv[])
{
  FILE          *fpin, *fpout;
  char          *outfile = 0;
  /* Scalars */
  Integer       i, ipiv_len, j, kl, ku, m, n, pdab;
  Integer       exit_status = 0;
  NagError      fail;
  Nag_OrderType order;

  /* Arrays */
  double        *ab = 0;
  Integer       *ipiv = 0;

#ifdef NAG_COLUMN_MAJOR
#define AB(I, J) ab[(J-1)*pdab + kl + ku + I - J]
  order = Nag_ColMajor;
#else
#define AB(I, J) ab[(I-1)*pdab + kl + J - I]
  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);
  (void) nag_example_file_io(argc, argv, "-nag_write", &outfile);
  fprintf(fpout, "nag_dgbtrf (f07bdc) Example Program Results\n\n");

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%ld%ld%ld%ld%*[^\n] ", &m, &n,
         &kl, &ku);
  ipiv_len = MIN(m, n);
  pdab = 2*kl + ku + 1;

  /* Allocate memory */
  if (!(ab = NAG_ALLOC((2*kl+ku+1) * MAX(m, n), double)) ||
      !(ipiv = NAG_ALLOC(ipiv_len, Integer)))
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A from data file */
  for (i = 1; i <= m; ++i)
    {
      for (j = MAX(i-kl, 1); j <= MIN(i+ku, n); ++j)
        fscanf(fpin, "%lf", &AB(i, j));
    }
  fscanf(fpin, "%*[^\n] ");

  /* Factorize A */
  /* nag_dgbtrf (f07bdc).
   * LU factorization of real m by n band matrix
   */
  nag_dgbtrf(order, m, n, kl, ku, ab, pdab, ipiv, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dgbtrf (f07bdc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print details of factorization */
  /* nag_band_real_mat_print (x04cec).
   * Print real packed banded matrix (easy-to-use)
   */
  if (outfile) fclose(fpout);
  nag_band_real_mat_print(order, m, n, kl, kl+ku, ab, pdab,
                          "Details of factorization", outfile, &fail);
  if (outfile && !(fpout = fopen(outfile, "a")))
    {
      exit_status = 2;
      goto END;
    }
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_band_real_mat_print (x04cec).\n%s\n",
              fail.message);
      exit_status = 1;
      goto END;
    }

  /* Print pivot indices */
  fprintf(fpout, "\n%s\n", "IPIV");
  for (i = 1; i <= MIN(m, n); ++i)
    fprintf(fpout, "%10ld%s", ipiv[i-1], i%7 == 0?"\n":" ");
  fprintf(fpout, "\n");

 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (ab) NAG_FREE(ab);
  if (ipiv) NAG_FREE(ipiv);
  return exit_status;
}