/* nag_dpbcon (f07hgc) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

#include <stdio.h>
#include <nag.h>
#include <nagx04.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagf16.h>
#include <nagx02.h>

int main(int argc, char *argv[])
{
  FILE          *fpin, *fpout;
  /* Scalars */
  Integer       i, j, k, kd, n, pdab;
  Integer       exit_status = 0;
  double        anorm, rcond;
  NagError      fail;
  Nag_UploType  uplo;
  Nag_OrderType order;
  /* Arrays */
  char          nag_enum_arg[40];
  double        *ab = 0;

#ifdef NAG_COLUMN_MAJOR
#define AB_UPPER(I, J) ab[(J-1)*pdab + k + I - J - 1]
#define AB_LOWER(I, J) ab[(J-1)*pdab + I - J]
  order = Nag_ColMajor;
#else
#define AB_UPPER(I, J) ab[(I-1)*pdab + J - I]
#define AB_LOWER(I, J) ab[(I-1)*pdab + k + J - I - 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);
  fprintf(fpout, "nag_dpbcon (f07hgc) Example Program Results\n\n");

  /* Skip heading in data file */
  fscanf(fpin, "%*[^\n] ");
  fscanf(fpin, "%ld%ld%*[^\n] ", &n, &kd);
  pdab = kd + 1;

  /* Allocate memory */
  if (!(ab = NAG_ALLOC((kd+1) * n, double)))
    {
      fprintf(fpout, "Allocation failure\n");
      exit_status = -1;
      goto END;
    }

  /* Read A from data file */
  fscanf(fpin, " %s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value(x04nac).
   * Converts NAG enum member name to value
   */
  uplo = (Nag_UploType) nag_enum_name_to_value(nag_enum_arg);

  k = kd + 1;
  if (uplo == Nag_Upper)
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = i; j <= MIN(i+kd, n); ++j)
            fscanf(fpin, "%lf", &AB_UPPER(i, j));
        }
      fscanf(fpin, "%*[^\n] ");
    }
  else
    {
      for (i = 1; i <= n; ++i)
        {
          for (j = MAX(1, i-kd); j <= i; ++j)
            fscanf(fpin, "%lf", &AB_LOWER(i, j));
        }
      fscanf(fpin, "%*[^\n] ");
    }
  /* Compute norm of A */
  /* nag_dsb_norm (f16rec).
   * 1-norm, infinity-norm, Frobenius norm, largest absolute
   * element, real symmetric band matrix
   */
  nag_dsb_norm(order, Nag_OneNorm, uplo, n, kd, ab, pdab, &anorm, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dsb_norm (f16rec).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Factorize A */
  /* nag_dpbtrf (f07hdc).
   * Cholesky factorization of real symmetric
   * positive-definite band matrix
   */
  nag_dpbtrf(order, uplo, n, kd, ab, pdab, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dpbtrf (f07hdc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Estimate condition number */
  /* nag_dpbcon (f07hgc).
   * Estimate condition number of real symmetric
   * positive-definite band matrix, matrix already factorized
   * by nag_dpbtrf (f07hdc)
   */
  nag_dpbcon(order, uplo, n, kd, ab, pdab, anorm, &rcond, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_dpbcon (f07hgc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* nag_machine_precision (x02ajc).
   * The machine precision
   */
  if (rcond >= X02AJC)
    fprintf(fpout, "Estimate of condition number =%11.2e\n\n", 1.0/rcond);
  else
    fprintf(fpout, "A is singular to working precision\n");
 END:
  if (fpin != stdin) fclose(fpin);
  if (fpout != stdout) fclose(fpout);
  if (ab) NAG_FREE(ab);
  return exit_status;
}