/* nag_matop_real_gen_matrix_cond_sqrt (f01jdc) Example Program.
 *
 * Copyright 2021 Numerical Algorithms Group.
 *
 * Mark 27.3, 2021.
 */
#include <nag.h>

#define A(I, J) a[J * pda + I]

int main(void) {
  /* Scalars */
  Integer exit_status = 0;
  Integer i, j, n, pda;
  double alpha, condsa;
  /* Arrays */
  double *a = 0;
  /* Nag Types */
  Nag_OrderType order = Nag_ColMajor;
  NagError fail;

  INIT_FAIL(fail);

  /* Output preamble */
  printf("nag_matop_real_gen_matrix_cond_sqrt (f01jdc) ");
  printf("Example Program Results\n\n");
  fflush(stdout);

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

  /* Read in the problem size */
  scanf("%" NAG_IFMT "%*[^\n]", &n);

  pda = n;
  if (!(a = NAG_ALLOC(pda * n, double))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* Read in the matrix A from data file */
  for (i = 0; i < n; i++)
    for (j = 0; j < n; j++)
      scanf("%lf", &A(i, j));
  scanf("%*[^\n] ");

  /* Find matrix square root, condition number and residual bound using
   * nag_matop_real_gen_matrix_cond_sqrt (f01jdc)
   * Condition number for the square root of a real matrix
   */
  nag_matop_real_gen_matrix_cond_sqrt(n, a, pda, &alpha, &condsa, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_matop_real_gen_matrix_cond_sqrt (f01jdc)\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print matrix sqrt(A) using nag_file_print_matrix_real_gen (x04cac)
   * Print real general matrix (easy-to-use)
   */
  nag_file_print_matrix_real_gen(order, Nag_GeneralMatrix, Nag_NonUnitDiag, n,
                                 n, a, pda, "sqrt(A)", NULL, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_file_print_matrix_real_gen (x04cac)\n%s\n",
           fail.message);
    exit_status = 2;
    goto END;
  }

  /* Print condition number estimates */
  printf("Estimated relative condition number is: %7.2f\n", condsa);
  printf("Condition number for the relative residual is: %7.2f\n", alpha);

END:
  NAG_FREE(a);
  return exit_status;
}