NAG Library Manual, Mark 28.3
Interfaces:  FL   CL   CPP   AD 

NAG CL Interface Introduction
Example description
/* nag_blast_dgemm (f16yac) Example Program.
 *
 * Copyright 2022 Numerical Algorithms Group.
 *
 * Mark 28.3, 2022.
 */

#include <nag.h>
#include <stdio.h>

int main(void) {

  /* Scalars */
  double alpha, beta;
  Integer exit_status, i, j, k, m, n, pda, pdb, pdc;

  /* Arrays */
  double *a = 0, *b = 0, *c = 0;
  char nag_enum_arg[40];

  /* Nag Types */
  NagError fail;
  Nag_OrderType order;
  Nag_TransType transa;
  Nag_TransType transb;

#ifdef NAG_COLUMN_MAJOR
#define A(I, J) a[(J - 1) * pda + I - 1]
#define B(I, J) b[(J - 1) * pdb + I - 1]
#define C(I, J) c[(J - 1) * pdc + I - 1]
  order = Nag_ColMajor;
#else
#define A(I, J) a[(I - 1) * pda + J - 1]
#define B(I, J) b[(I - 1) * pdb + J - 1]
#define C(I, J) c[(I - 1) * pdc + J - 1]
  order = Nag_RowMajor;
#endif

  exit_status = 0;
  INIT_FAIL(fail);

  printf("nag_blast_dgemm (f16yac) Example Program Results\n\n");

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

  /* Read the problem dimensions */
  scanf("%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &m, &n, &k);

  /* Read the transpose parameters */
  scanf("%39s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value (x04nac).
   * Converts NAG enum member name to value
   */
  transa = (Nag_TransType)nag_enum_name_to_value(nag_enum_arg);
  scanf("%39s%*[^\n] ", nag_enum_arg);
  /* nag_enum_name_to_value (x04nac).
   * Converts NAG enum member name to value
   */
  transb = (Nag_TransType)nag_enum_name_to_value(nag_enum_arg);
  /* Read scalar parameters */
  scanf("%lf%lf%*[^\n] ", &alpha, &beta);

#ifdef NAG_COLUMN_MAJOR
  pdc = m;
  if (transa == Nag_NoTrans && transb == Nag_NoTrans) {
    pda = m;
    pdb = k;
  } else if ((transa == Nag_Trans || transa == Nag_ConjTrans) &&
             transb == Nag_NoTrans) {
    pda = k;
    pdb = k;
  } else if (transa == Nag_NoTrans &&
             (transb == Nag_Trans || transb == Nag_ConjTrans)) {
    pda = m;
    pdb = n;
  } else {
    pda = k;
    pdb = n;
  }
#else
  pdc = n;
  if (transa == Nag_NoTrans && transb == Nag_NoTrans) {
    pda = k;
    pdb = n;
  } else if ((transa == Nag_Trans || transa == Nag_ConjTrans) &&
             transb == Nag_NoTrans) {
    pda = m;
    pdb = n;
  } else if (transa == Nag_NoTrans &&
             (transb == Nag_Trans || transb == Nag_ConjTrans)) {
    pda = k;
    pdb = k;
  } else {
    pda = m;
    pdb = k;
  }
#endif

  if (m > 0 && n > 0) {
    /* Allocate memory */
    if (!(a = NAG_ALLOC(m * k, double)) || !(b = NAG_ALLOC(n * k, double)) ||
        !(c = NAG_ALLOC(m * n, double))) {
      printf("Allocation failure\n");
      exit_status = -1;
      goto END;
    }
  } else {
    printf("Invalid m, n or k\n");
    exit_status = 1;
    return exit_status;
  }

  /* Input matrix A */
  if (transa == Nag_NoTrans) {
    for (i = 1; i <= m; ++i) {
      for (j = 1; j <= k; ++j)
        scanf("%lf", &A(i, j));
      scanf("%*[^\n] ");
    }
  } else {
    for (i = 1; i <= k; ++i) {
      for (j = 1; j <= m; ++j)
        scanf("%lf", &A(i, j));
      scanf("%*[^\n] ");
    }
  }

  /* Input matrix B */
  if (transb == Nag_NoTrans) {
    for (i = 1; i <= k; ++i) {
      for (j = 1; j <= n; ++j)
        scanf("%lf", &B(i, j));
      scanf("%*[^\n] ");
    }
  } else {
    for (i = 1; i <= n; ++i) {
      for (j = 1; j <= k; ++j)
        scanf("%lf", &B(i, j));
      scanf("%*[^\n] ");
    }
  }

  /* Input matrix C */
  for (i = 1; i <= m; ++i) {
    for (j = 1; j <= n; ++j)
      scanf("%lf", &C(i, j));
    scanf("%*[^\n] ");
  }

  /* nag_blast_dgemm (f16yac).
   * Matrix-matrix multiply.
   *
   */
  nag_blast_dgemm(order, transa, transb, m, n, k, alpha, a, pda, b, pdb, beta,
                  c, pdc, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_blast_dgemm.\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print result */
  /* nag_file_print_matrix_real_gen (x04cac).
   * Print real general matrix (easy-to-use)
   */
  fflush(stdout);
  nag_file_print_matrix_real_gen(order, Nag_GeneralMatrix, Nag_NonUnitDiag, m,
                                 n, c, pdc, "Matrix Matrix Product", 0, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_file_print_matrix_real_gen (x04cac).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }

END:
  NAG_FREE(a);
  NAG_FREE(b);
  NAG_FREE(c);

  return exit_status;
}