```/* nag_sparse_herm_chol_sol (f11jqc) Example Program.
*
* Copyright 2017 Numerical Algorithms Group.
*
* Mark 26.1, 2017.
*/

#include <nag.h>
#include <nag_stdlib.h>
#include <naga02.h>
#include <nagf11.h>

int main(void)
{
/* Scalars */
Integer exit_status = 0;
double dscale, dtol, rnorm, tol;
Integer i, itn, la, lfill, maxitn, n, nnz, nnzc, npivm;
/* Arrays */
char nag_enum_arg[40];
Complex *a = 0, *b = 0, *x = 0;
Integer *icol = 0, *ipiv = 0, *irow = 0, *istr = 0;
/* NAG types */
Nag_SparseSym_Method method;
Nag_SparseSym_Piv pstrat;
Nag_SparseSym_Fact mic;
NagError fail;

INIT_FAIL(fail);

printf("nag_sparse_herm_chol_sol (f11jqc) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%" NAG_IFMT "%*[^\n]", &n);
scanf("%" NAG_IFMT "%*[^\n]", &nnz);

/* Allocate memory */
la = 3 * nnz;
if (!(a = NAG_ALLOC(la, Complex)) ||
!(b = NAG_ALLOC(n, Complex)) ||
!(x = NAG_ALLOC(n, Complex)) ||
!(icol = NAG_ALLOC(la, Integer)) ||
!(ipiv = NAG_ALLOC(n, Integer)) ||
!(irow = NAG_ALLOC(la, Integer)) || !(istr = NAG_ALLOC(n + 1, Integer))
)
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
scanf("%39s%*[^\n]", nag_enum_arg);
/* nag_enum_name_to_value (x04nac).
* Converts NAG enum member name to value
*/
method = (Nag_SparseSym_Method) nag_enum_name_to_value(nag_enum_arg);
scanf("%" NAG_IFMT "%lf%*[^\n]", &lfill, &dtol);
scanf("%39s%*[^\n]", nag_enum_arg);
mic = (Nag_SparseSym_Fact) nag_enum_name_to_value(nag_enum_arg);
scanf("%lf%*[^\n]", &dscale);
scanf("%39s%*[^\n]", nag_enum_arg);
pstrat = (Nag_SparseSym_Piv) nag_enum_name_to_value(nag_enum_arg);
scanf("%lf%" NAG_IFMT "%*[^\n]", &tol, &maxitn);

/* 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 rhs vector b and initial approximate solution x */
for (i = 0; i < n; i++)
scanf(" ( %lf , %lf ) ", &b[i].re, &b[i].im);
scanf("%*[^\n]");
for (i = 0; i < n; i++)
scanf(" ( %lf , %lf ) ", &x[i].re, &x[i].im);

/* Calculate incomplete Cholesky factorization of complex sparse Hermitian
* matrix using nag_sparse_herm_chol_fac (f11jnc).
*/
nag_sparse_herm_chol_fac(n, nnz, a, la, irow, icol, lfill, dtol, mic,
dscale, pstrat, ipiv, istr, &nnzc, &npivm, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_sparse_herm_chol_fac (f11jnc).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}
/* Solve Linear System. */
/* nag_sparse_herm_chol_sol (f11jqc).
* Solution of complex sparse Hermitian linear system, conjugate
* gradient/Lanczos method, preconditioner computed by f11jnc
*/
nag_sparse_herm_chol_sol(method, n, nnz, a, la, irow, icol, ipiv, istr,
b, tol, maxitn, x, &rnorm, &itn, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_sparse_herm_chol_sol.(f11jqc)\n%s\n",
fail.message);
exit_status = 2;
goto END;
}
printf("Converged in  %10" NAG_IFMT " iterations \n", itn);
printf("Final residual norm = %10.3e\n\n", rnorm);
printf("     Converged Solution\n");
/* Output x */
for (i = 0; i < n; i++)
printf(" (%13.4e, %13.4e)\n", x[i].re, x[i].im);

END:
NAG_FREE(a);
NAG_FREE(b);
NAG_FREE(x);
NAG_FREE(icol);
NAG_FREE(ipiv);
NAG_FREE(irow);
NAG_FREE(istr);
return exit_status;
}
```