NAG Library Manual, Mark 28.5
Interfaces:  FL   CL   CPP   AD 

NAG CL Interface Introduction
Example description
/* nag_lapacklin_zgetri (f07awc) Example Program.
 *
 * Copyright 2022 Numerical Algorithms Group.
 *
 * Mark 28.5, 2022.
 */

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

int main(void) {
  /* Scalars */
  Integer i, ipiv_len, j, n, pda;
  Integer exit_status = 0;
  NagError fail;
  Nag_OrderType order;
  /* Arrays */
  Complex *a = 0;
  Integer *ipiv = 0;

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

  INIT_FAIL(fail);

  printf("nag_lapacklin_zgetri (f07awc) Example Program Results\n\n");

  /* Skip heading in data file */
  scanf("%*[^\n] ");
  scanf("%" NAG_IFMT "%*[^\n] ", &n);
#ifdef NAG_COLUMN_MAJOR
  pda = n;
#else
  pda = n;
#endif
  ipiv_len = n;

  /* Allocate memory */
  if (!(a = NAG_ALLOC(n * n, Complex)) ||
      !(ipiv = NAG_ALLOC(ipiv_len, Integer))) {
    printf("Allocation failure\n");
    exit_status = -1;
    goto END;
  }

  /* Read A from data file */
  for (i = 1; i <= n; ++i) {
    for (j = 1; j <= n; ++j)
      scanf(" ( %lf , %lf )", &A(i, j).re, &A(i, j).im);
  }
  scanf("%*[^\n] ");

  /* Factorize A */
  /* nag_lapacklin_zgetrf (f07arc).
   * LU factorization of complex m by n matrix
   */
  nag_lapacklin_zgetrf(order, n, n, a, pda, ipiv, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_zgetrf (f07arc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Compute inverse of A */
  /* nag_lapacklin_zgetri (f07awc).
   * Inverse of complex matrix, matrix already factorized by
   * nag_lapacklin_zgetrf (f07arc)
   */
  nag_lapacklin_zgetri(order, n, a, pda, ipiv, &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_lapacklin_zgetri (f07awc).\n%s\n", fail.message);
    exit_status = 1;
    goto END;
  }

  /* Print inverse */
  /* nag_file_print_matrix_complex_gen_comp (x04dbc).
   * Print complex general matrix (comprehensive)
   */
  fflush(stdout);
  nag_file_print_matrix_complex_gen_comp(
      order, Nag_GeneralMatrix, Nag_NonUnitDiag, n, n, a, pda, Nag_BracketForm,
      "%7.4f", "Inverse", Nag_IntegerLabels, 0, Nag_IntegerLabels, 0, 80, 0, 0,
      &fail);
  if (fail.code != NE_NOERROR) {
    printf("Error from nag_file_print_matrix_complex_gen_comp (x04dbc).\n%s\n",
           fail.message);
    exit_status = 1;
    goto END;
  }
END:
  NAG_FREE(a);
  NAG_FREE(ipiv);
  return exit_status;
}