/* nag_matop_real_gen_matrix_actexp_rcomm (f01gbc) Example Program.
 *
 * Copyright 2024 Numerical Algorithms Group.
 *
 * Mark 30.1, 2024.
 */

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

int main(void) {

  /* Scalars */
  Integer exit_status = 0, irevcm = 0;
  Integer i, j, m, n, nnz, ldb, ldb2, ldx, ldy;
  double one = 1.0, zero = 0.0;
  double t, tr;

  /* Arrays */
  double *a = 0, *b = 0, *b2 = 0, *comm = 0;
  double *p = 0, *r = 0, *x = 0, *y = 0, *z = 0;
  Integer *icolzp = 0, *irowix = 0, *icomm = 0;

  /* Nag Types */
  NagError fail, fail2;
  Nag_OrderType order = Nag_ColMajor;
  Nag_TransType tran = Nag_Trans, notran = Nag_NoTrans;

  INIT_FAIL(fail);
  INIT_FAIL(fail2);

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

  /* Output preamble */
  printf("nag_matop_real_gen_matrix_actexp_rcomm (f01gbc) ");
  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);

  ldb = ldb2 = ldx = ldy = n;

  if (!(b = NAG_ALLOC(n * m, double)) || !(b2 = NAG_ALLOC(n * m, double)) ||
      !(comm = NAG_ALLOC(n * m + 3 * n + 12, double)) ||
      !(p = NAG_ALLOC(n, double)) || !(r = NAG_ALLOC(n, double)) ||
      !(x = NAG_ALLOC(n * 2, double)) || !(y = NAG_ALLOC(n * 2, double)) ||
      !(z = NAG_ALLOC(n, double)) || !(icolzp = NAG_ALLOC(n + 1, Integer)) ||
      !(icomm = NAG_ALLOC(2 * n + 40, Integer))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* Read in the sparse matrix a in compressed column format */
  for (i = 0; i < n + 1; ++i)
    scanf("%" NAG_IFMT "", &icolzp[i]);
  scanf("%*[^\n]");

  nnz = icolzp[n] - 1;

  if (!(a = NAG_ALLOC(nnz, double)) || !(irowix = NAG_ALLOC(nnz, Integer))) {
    printf("Allocation failure\n");
    exit_status = -2;
    goto END;
  }

  for (i = 0; i < nnz; ++i)
    scanf("%lf %" NAG_IFMT "%*[^\n]", &a[i], &irowix[i]);

  /* 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]");

  /* Compute the trace of A */
  tr = 0.0;
  j = 1;
  for (i = 0; i < nnz; ++i) {
    /* new column? */
    if (icolzp[j] <= i + 1)
      j++;
    /* diagonal element? */
    if (irowix[i] == j)
      tr += a[i];
  }

  /* Find exp(tA) B using
   * nag_matop_real_gen_matrix_actexp_rcomm (f01gbc):
   *     Action of the exponential of a complex matrix on a complex matrix.
   *
   * Sparse matrix multiplies are performed using
   * nag_sparse_direct_real_gen_matmul (f11mkc):
   *     Real sparse nonsymmetric matrix matrix multiply, compressed column
   *     storage.
   */
  while (1) {
    nag_matop_real_gen_matrix_actexp_rcomm(&irevcm, n, m, b, ldb, t, tr, b2,
                                           ldb2, x, ldx, y, ldy, p, r, z, comm,
                                           icomm, &fail);
    switch (irevcm) {
    case 0:
      /* Final exit. */
      goto END_REVCM;
      break;
    case 1:
      /* Compute AB and store in B2 */
      nag_sparse_direct_real_gen_matmul(order, notran, n, m, one, icolzp,
                                        irowix, a, b, ldb, zero, b2, ldb2,
                                        &fail2);
      break;
    case 2:
      /* Compute AX and store in Y */
      nag_sparse_direct_real_gen_matmul(order, notran, n, 2, one, icolzp,
                                        irowix, a, x, ldx, zero, y, ldy,
                                        &fail2);
      break;
    case 3:
      /* Compute A^T Y and store in X */
      nag_sparse_direct_real_gen_matmul(order, tran, n, 2, one, icolzp, irowix,
                                        a, y, ldy, zero, x, ldx, &fail2);
      break;
    case 4:
      /* Compute AZ and store in P */
      nag_sparse_direct_real_gen_matmul(order, notran, n, 1, one, icolzp,
                                        irowix, a, z, n, zero, p, n, &fail2);
      break;
    case 5:
      /* Compute A^T Z and store in R */
      nag_sparse_direct_real_gen_matmul(order, tran, n, 1, one, icolzp, irowix,
                                        a, z, n, zero, r, n, &fail2);
    }
    if (fail2.code != NE_NOERROR) {
      printf("Error from nag_sparse_direct_real_gen_matmul (f11mkc).\n%s\n",
             fail2.message);
      exit_status = 1;
      goto END;
    }
  }
END_REVCM:

  if (fail.code != NE_NOERROR) {
    printf("Error from nag_matop_real_gen_matrix_actexp_rcomm (f01gbc)\n%s\n",
           fail.message);
    exit_status = 2;
    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 = 3;
    goto END;
  }

END:
  NAG_FREE(a);
  NAG_FREE(b);
  NAG_FREE(b2);
  NAG_FREE(p);
  NAG_FREE(r);
  NAG_FREE(x);
  NAG_FREE(y);
  NAG_FREE(z);
  NAG_FREE(comm);
  NAG_FREE(icolzp);
  NAG_FREE(irowix);
  NAG_FREE(icomm);
  return exit_status;
}