/* nag_matop_real_gen_matrix_actexp (f01gac) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.3, 2024.
 */

#include <math.h>
#include <nag.h>

int main(void) {

  /* Scalars */
  Integer exit_status = 0;
  Integer i, j, m, n, lda, ldb;
  double t;

  /* Arrays */
  double *a = 0;
  double *b = 0;

  /* Nag Types */
  Nag_OrderType order;
  NagError fail;

  INIT_FAIL(fail);

#define A(I, J) a[(J - 1) * lda + I - 1]
#define B(I, J) b[(J - 1) * ldb + I - 1]

  order = Nag_ColMajor;

  /* Output preamble */
  printf("nag_matop_real_gen_matrix_actexp (f01gac) ");
  printf("Example Program Results\n\n");
  fflush(stdout);

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

  /* Read in the problem size and the value of the parameter t */
  scanf("%" NAG_IFMT " %" NAG_IFMT " %lf%*[^\n]", &n, &m, &t);

  lda = n;
  ldb = n;

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

  /* Read in the matrix a from data file */
  for (i = 1; i <= n; i++)
    for (j = 1; j <= n; j++)
      scanf("%lf", &A(i, j));
  scanf("%*[^\n]");

  /* Read in the matrix b from data file */
  for (i = 1; i <= n; i++)
    for (j = 1; j <= m; j++)
      scanf("%lf", &B(i, j));
  scanf("%*[^\n]");

  /* Find exp(tA) B using
   * nag_matop_real_gen_matrix_actexp (f01gac)
   * Action of the exponential of a real matrix on a real matrix
   */
  nag_matop_real_gen_matrix_actexp(n, m, a, lda, b, ldb, t, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_matop_real_gen_matrix_actexp (f01gac)\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print solution 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,
                                 m, b, ldb, "exp(tA) B", 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;
  }

END:
  NAG_FREE(a);
  NAG_FREE(b);
  return exit_status;
}