```/* nag_zgtcon (f07cuc) Example Program.
*
* Copyright 2014 Numerical Algorithms Group.
*
* Mark 23, 2011.
*
*/
#include <stdio.h>
#include <math.h>
#include <nag.h>
#include <nag_stdlib.h>
#include <nagf07.h>
#include <nagx02.h>

int main(void)
{
/* Scalars */
double   anorm, rcond;
Integer  exit_status = 0, i, n;

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

/* Nag Types */
NagError fail;

#define CABS(dl) sqrt(dl.re * dl.re + dl.im * dl.im)

INIT_FAIL(fail);

printf("nag_zgtcon (f07cuc) Example Program Results\n\n");
/* Skip heading in data file */
scanf("%*[^\n]");
scanf("%ld%*[^\n]", &n);
if (n < 0)
{
printf("Invalid n\n");
exit_status = -2;
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]");

/* Compute the 1-norm of A */

if (n == 1)
{
anorm = CABS(d[0]);
}
else
{
anorm = MAX(CABS(d[0])+CABS(dl[0]), CABS(d[n-1])+CABS(du[n-2]));
for (i = 1; i < n-1; ++i)
anorm = MAX(anorm, CABS(d[i])+CABS(dl[i])+CABS(du[i-1]));
}
/* nag_zgttrf (f07crc)
* LU factorization of complex tridiagonal matrix A
*/
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;
}

/* Estimate the condition number of A using
* nag_zgtcon (f07cuc).
* Estimates the reciprocal of the condition number of a LU factorized
* complex tridiagonal matrix.
*/
nag_zgtcon(Nag_OneNorm, n, dl, d, du, du2, ipiv, anorm, &rcond, &fail);
if (fail.code != NE_NOERROR)
{
printf("Error from nag_zgtcon (f07cuc).\n%s\n", fail.message);
exit_status = 2;
goto END;
}

/* Print the estimated condition number */
if (rcond >= nag_machine_precision)
printf("Estimate of condition number = %11.2e\n\n", 1.0/rcond);
else
printf("A is singular to working precision. RCOND = %11.2e\n\n", rcond);
END:
NAG_FREE(d);
NAG_FREE(dl);
NAG_FREE(du);
NAG_FREE(du2);
NAG_FREE(ipiv);

return exit_status;
}
```