/* nag_zgbcon (f07buc) Example Program.
 *
 * Copyright 2001 Numerical Algorithms Group.
 *
 * Mark 7, 2001.
 */

#include <stdio.h>
#include <nag.h>
#include <nagx04.h>
#include <nag_stdlib.h>
#include <naga02.h>
#include <nagf07.h>
#include <nagx02.h>

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

  /* Arrays */
  Complex       *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);
  fprintf(fpout, "nag_zgbcon (f07buc) Example Program Results\n\n");

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

  /* Allocate memory */
  if (!(ab = NAG_ALLOC((2*kl+ku+1) * n, Complex)) ||
      !(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 <= n; ++i)
    {
      for (j = MAX(i-kl, 1); j <= MIN(i+ku, n); ++j)
        fscanf(fpin, " ( %lf , %lf )", &AB(i, j).re, &AB(i, j).im);
    }
  fscanf(fpin, "%*[^\n] ");
  /* Compute norm of A */
  anorm = 0.0;
  for (j = 1; j <= n; ++j)
    {
      sum = 0.0;
      for (i = MAX(j-ku, 1); i <= MIN(j+kl, n); ++i)
        /* nag_complex_abs (a02dbc).
         * Modulus of a complex number
         */
        sum = sum + nag_complex_abs(AB(i, j));
      anorm = MAX(anorm, sum);
    }
  /* Factorize A */
  /* nag_zgbtrf (f07brc).
   * LU factorization of complex m by n band matrix
   */
  nag_zgbtrf(order, n, n, kl, ku, ab, pdab, ipiv, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_zgbtrf (f07brc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Estimate condition number */
  /* nag_zgbcon (f07buc).
   * Estimate condition number of complex band matrix, matrix
   * already factorized by nag_zgbtrf (f07brc)
   */
  nag_zgbcon(order, Nag_OneNorm, n, kl, ku, ab, pdab, ipiv,
             anorm, &rcond, &fail);
  if (fail.code != NE_NOERROR)
    {
      fprintf(fpout, "Error from nag_zgbcon (f07buc).\n%s\n", fail.message);
      exit_status = 1;
      goto END;
    }
  /* Print condition number */
  /* nag_machine_precision (x02ajc).
   * The machine precision
   */
  if (rcond > X02AJC)
    fprintf(fpout, "Estimate of condition number = %11.2e\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);
  if (ipiv) NAG_FREE(ipiv);
  return exit_status;
}