```/* nag_zgttrf (f07crc) Example Program.
*
* Copyright 2017 Numerical Algorithms Group.
*
* Mark 26.1, 2017.
*/

#include <stdio.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>

int main(void)
{

/* Scalars */
Integer exit_status = 0, i, n;

/* Arrays */
Complex *d = 0, *dl = 0, *du = 0, *du2 = 0;
Integer *ipiv = 0;

/* Nag Types */
NagError fail;

INIT_FAIL(fail);

printf("nag_zgttrf (f07crc) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%" NAG_IFMT "%*[^\n]", &n);
if (n < 0) {
printf("Invalid n\n");
exit_status = 1;
goto END;
}

/* Allocate memory */
if (!(d = NAG_ALLOC(n, Complex)) ||
!(dl = NAG_ALLOC(n - 1, Complex)) ||
!(du = NAG_ALLOC(n - 1, Complex)) ||
!(du2 = NAG_ALLOC(n - 2, Complex)) || !(ipiv = NAG_ALLOC(n, Integer)))
{
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/* Read the tridiagonal matrix A from data file */
for (i = 0; i < n - 1; ++i)
scanf(" ( %lf , %lf )", &du[i].re, &du[i].im);
scanf("%*[^\n]");
for (i = 0; i < n; ++i)
scanf(" ( %lf , %lf )", &d[i].re, &d[i].im);
scanf("%*[^\n]");
for (i = 0; i < n - 1; ++i)
scanf(" ( %lf , %lf )", &dl[i].re, &dl[i].im);
scanf("%*[^\n]");

/* Factorize the tridiagonal matrix A using nag_zgttrf (f07crc). */
nag_zgttrf(n, dl, d, du, du2, ipiv, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_zgttrf (f07crc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Print details of the factorization */
printf("Details of factorization (U)\n\n");

printf("%17s%24s%22s\n", "Main diagonal", "First superdiagonal",
"Second superdiagonal");
for (i = 0; i < n; ++i) {
printf("(%8.4f, %8.4f)", d[i].re, d[i].im);
if (i < n - 1)
printf(" (%8.4f, %8.4f)", du[i].re, du[i].im);
if (i < n - 2)
printf(" (%8.4f, %8.4f)", du2[i].re, du2[i].im);
printf("\n");
}

printf("\n Multipliers\n");
for (i = 0; i < n - 1; ++i)
printf("(%8.4f, %8.4f)\n", dl[i].re, dl[i].im);

printf("\n Vector of interchanges\n");
for (i = 0; i < n; ++i)
printf("%7" NAG_IFMT "%s", ipiv[i], i % 5 == 4 ? "\n" : " ");
printf("\n");
END:
NAG_FREE(d);
NAG_FREE(dl);
NAG_FREE(du);
NAG_FREE(du2);
NAG_FREE(ipiv);

return exit_status;
}
```