/* nag_lapacklin_dptcon (f07jgc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.2, 2024.
 *
 * UNFINISHED - replace commented out climp calls
 */
#include <nag.h>
#include <stdio.h>

int main(void) {
  /* Scalars */
  double anorm, rcond;
  Integer exit_status = 0, i, n;

  /* Arrays */
  double *d = 0, *e = 0;

  /* Nag Types */
  NagError fail;

  INIT_FAIL(fail);

  printf("nag_lapacklin_dptcon (f07jgc) Example Program Results\n\n");
  /* Skip heading in data file */
  scanf("%*[^\n]");
  scanf("%" NAG_IFMT "%*[^\n]", &n);
  if (n < 0) {
    printf("Invalid n\n");
    exit_status = 1;
    goto END;
  }
  /* Allocate memory */
  if (!(d = NAG_ALLOC(n, double)) || !(e = NAG_ALLOC(n - 1, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* Read the lower bidiagonal part of the tridiagonal matrix A from */
  /* data file */
  for (i = 0; i < n; ++i)
    scanf("%lf", &d[i]);
  scanf("%*[^\n]");
  for (i = 0; i < n - 1; ++i)
    scanf("%lf", &e[i]);
  scanf("%*[^\n]");

  /* Compute the 1-norm of A */
  anorm = MAX(ABS(d[0]) + ABS(e[0]), ABS(e[n - 2]) + ABS(d[n - 1]));
  for (i = 1; i < n - 1; ++i)
    anorm = MAX(anorm, ABS(d[i]) + ABS(e[i]) + ABS(e[i - 1]));

  /* Factorize the tridiagonal matrix A using nag_lapacklin_dgbsv (f07bac). */
  nag_lapacklin_dpttrf(n, d, e, &fail);

  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dgbsv (f07bac).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Estimate the condition number of A using nag_lapacklin_dptcon (f07jgc). */
  nag_lapacklin_dptcon(n, d, e, anorm, &rcond, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_dptcon (f07jgc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print the estimated condition number */
  if (rcond >= nag_machine_precision)
    printf("Estimate of condition number = %11.2e\n\n", 1.0 / rcond);
  else
    printf("A is singular to working precision. RCOND = %11.2e\n\n", rcond);

END:
  NAG_FREE(d);
  NAG_FREE(e);

  return exit_status;
}