NAG Library Manual, Mark 30.1
```/* nag_lapackeig_zgebrd (f08ksc) Example Program.
*
* Copyright 2024 Numerical Algorithms Group.
*
* Mark 30.1, 2024.
*/

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

int main(void) {
/* Scalars */
Integer i, j, m, n, pda, d_len, e_len, tauq_len, taup_len;
Integer exit_status = 0;
NagError fail;
Nag_OrderType order;
/* Arrays */
Complex *a = 0, *taup = 0, *tauq = 0;
double *d = 0, *e = 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_lapackeig_zgebrd (f08ksc) Example Program Results\n");

/* Skip heading in data file */
scanf("%*[^\n] ");
scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &m, &n);
#ifdef NAG_COLUMN_MAJOR
pda = m;
#else
pda = n;
#endif
d_len = MIN(m, n);
e_len = MIN(m, n) - 1;
tauq_len = MIN(m, n);
taup_len = MIN(m, n);

/* Allocate memory */
if (!(a = NAG_ALLOC(m * n, Complex)) || !(d = NAG_ALLOC(d_len, double)) ||
!(e = NAG_ALLOC(e_len, double)) ||
!(taup = NAG_ALLOC(taup_len, Complex)) ||
!(tauq = NAG_ALLOC(tauq_len, Complex))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

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

/* Reduce A to bidiagonal form */
/* nag_lapackeig_zgebrd (f08ksc).
* Unitary reduction of complex general rectangular matrix
* to bidiagonal form
*/
nag_lapackeig_zgebrd(order, m, n, a, pda, d, e, tauq, taup, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_lapackeig_zgebrd (f08ksc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Print bidiagonal form */
printf("\nDiagonal\n");
for (i = 1; i <= MIN(m, n); ++i)
printf("%9.4f%s", d[i - 1], i % 8 == 0 ? "\n" : " ");
if (m >= n)
printf("\nSuperdiagonal\n");
else
printf("\nSubdiagonal\n");
for (i = 1; i <= MIN(m, n) - 1; ++i)
printf("%9.4f%s", e[i - 1], i % 8 == 0 ? "\n" : " ");
printf("\n");

END:
NAG_FREE(a);
NAG_FREE(d);
NAG_FREE(e);
NAG_FREE(taup);
NAG_FREE(tauq);

return exit_status;
}
```