```/* nag_sparse_complex_herm_matvec (f11xsc) Example Program.
*
* Copyright 2020 Numerical Algorithms Group.
*
* Mark 27.1, 2020.
*/

#include <nag.h>

int main(void) {
/* Scalars */
Integer exit_status = 0;
Integer i, j, n, nnz;
/* Arrays */
char nag_enum_arg[40];
Integer *irow = 0, *icol = 0;
Complex *a = 0, *x = 0, *y = 0;
/* NAG types */
NagError fail;
Nag_SparseSym_CheckData check;

INIT_FAIL(fail);

printf("nag_sparse_complex_herm_matvec (f11xsc) Example Program Results\n");

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

/* Read order of matrix and number of nonzero entries */
scanf("%" NAG_IFMT "%*[^\n]", &n);
scanf("%" NAG_IFMT "%*[^\n]", &nnz);

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

/* Read the matrix A */
for (i = 0; i < nnz; i++)
scanf(" ( %lf , %lf ) %" NAG_IFMT "%" NAG_IFMT "%*[^\n]", &a[i].re,
&a[i].im, &irow[i], &icol[i]);

/* Read the vector x */
for (j = 0; j < n; j++)
scanf(" ( %lf , %lf ) ", &x[j].re, &x[j].im);
scanf("%*[^\n]");

/* Calculate matrix-vector product */
/* Nag_SparseSym_Check */
scanf("%39s%*[^\n]", nag_enum_arg);
check = (Nag_SparseSym_CheckData)nag_enum_name_to_value(nag_enum_arg);

/* nag_sparse_complex_herm_matvec (f11xsc)
* Complex sparse Hermitian matrix vector multiply.
*/
nag_sparse_complex_herm_matvec(n, nnz, a, irow, icol, check, x, y, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_sparse_complex_herm_matvec (f11xsc)\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

/* Output results */
printf(" Matrix-vector product\n");
for (j = 0; j < n; j++)
printf(" (%13.4e, %13.4e)\n", y[j].re, y[j].im);

END:
NAG_FREE(a);
NAG_FREE(x);
NAG_FREE(y);
NAG_FREE(icol);
NAG_FREE(irow);

return exit_status;
}
```