NAG Library Manual, Mark 27.2
```/* nag_surviv_coxmodel_risksets (g12zac) Example Program.
*
* Copyright 2021 Numerical Algorithms Group.
*
* Mark 27.2, 2021.
*/

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

int main(void) {
/* Scalars */
double dev, tol;
Integer exit_status, i, ip, iprint, j, lisi, m, maxit, mxn, n, nd, ns, num,
nxs, pdx, pdz;
NagError fail;
Nag_OrderType order;

/* Arrays */
double *b = 0, *cov = 0, *sc = 0, *se = 0, *t = 0, *tp = 0, *x = 0, *z = 0;
Integer *ic = 0, *id = 0, *irs = 0, *isi = 0, *isz = 0, *ixs = 0, *nca = 0,
*nct = 0;

#ifdef NAG_COLUMN_MAJOR
#define Z(I, J) z[(J - 1) * pdz + I - 1]
order = Nag_ColMajor;
#else
#define Z(I, J) z[(I - 1) * pdz + J - 1]
order = Nag_RowMajor;
#endif

INIT_FAIL(fail);

exit_status = 0;

printf("nag_surviv_coxmodel_risksets (g12zac) Example Program Results\n");

/* Skip heading in data file */
scanf("%*[^\n] ");
scanf("%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT "%" NAG_IFMT
"%*[^\n] ",
&n, &m, &ns, &maxit, &iprint);

/* Allocate arrays t, z, ic and isi */
if (ns > 0)
lisi = n;
else
lisi = 1;
if (!(t = NAG_ALLOC(n, double)) || !(z = NAG_ALLOC(n * n, double)) ||
!(ic = NAG_ALLOC(n, Integer)) || !(isi = NAG_ALLOC(lisi, Integer)) ||
!(isz = NAG_ALLOC(m, Integer))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

if (order == Nag_ColMajor) {
pdz = n;
} else {
pdz = m;
}

if (ns > 0) {
for (i = 1; i <= n; ++i) {
scanf("%lf", &t[i - 1]);
for (j = 1; j <= m; ++j)
scanf("%lf", &Z(i, j));
scanf("%" NAG_IFMT "%" NAG_IFMT "%*[^\n] ", &ic[i - 1], &isi[i - 1]);
}
} else {
for (i = 1; i <= n; ++i) {
scanf("%lf", &t[i - 1]);
for (j = 1; j <= m; ++j)
scanf("%lf", &Z(i, j));
scanf("%" NAG_IFMT "%*[^\n] ", &ic[i - 1]);
}
}

for (i = 1; i <= m; ++i)
scanf("%" NAG_IFMT "", &isz[i - 1]);
scanf("%" NAG_IFMT "%*[^\n] ", &ip);

/* Allocate other arrays for nag_surviv_coxmodel_risksets (g12zac) */
mxn = 1000;

if (order == Nag_ColMajor) {
pdx = mxn;
} else {
pdx = ip;
}

if (!(cov = NAG_ALLOC(ip * (ip + 1) / 2, double)) ||
!(sc = NAG_ALLOC(ip, double)) || !(se = NAG_ALLOC(ip, double)) ||
!(tp = NAG_ALLOC(n, double)) || !(x = NAG_ALLOC(mxn * ip, double)) ||
!(id = NAG_ALLOC(mxn, Integer)) || !(irs = NAG_ALLOC(n, Integer)) ||
!(ixs = NAG_ALLOC(mxn, Integer))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

/* nag_surviv_coxmodel_risksets (g12zac).
* Creates the risk sets associated with the Cox
* proportional hazards model for fixed covariates
*/
nag_surviv_coxmodel_risksets(order, n, m, ns, z, pdz, isz, ip, t, ic, isi,
&num, ixs, &nxs, x, mxn, id, &nd, tp, irs,
&fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_surviv_coxmodel_risksets (g12zac).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

/* Allocate arrays for nag_contab_condl_logistic (g11cac) */
if (!(b = NAG_ALLOC(ip, double)) || !(nca = NAG_ALLOC(nxs, Integer)) ||
!(nct = NAG_ALLOC(nxs, Integer))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}

for (i = 1; i <= ip; ++i)
scanf("%lf", &b[i - 1]);
scanf("%*[^\n] ");

tol = 1e-5;
/* nag_contab_condl_logistic (g11cac).
* Returns parameter estimates for the conditional analysis
* of stratified data
*/
nag_contab_condl_logistic(order, num, ip, nxs, x, pdx, isz, ip, id, ixs, &dev,
b, se, sc, cov, nca, nct, tol, maxit, iprint, 0,
&fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_contab_condl_logistic (g11cac).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}

printf("\n");
printf(" Parameter      Estimate       Standard Error\n");
printf("\n");
for (i = 1; i <= ip; ++i)
printf("%5" NAG_IFMT "          %8.4f          %8.4f          \n", i,
b[i - 1], se[i - 1]);

END:
NAG_FREE(b);
NAG_FREE(cov);
NAG_FREE(sc);
NAG_FREE(se);
NAG_FREE(t);
NAG_FREE(tp);
NAG_FREE(x);
NAG_FREE(z);
NAG_FREE(ic);
NAG_FREE(id);
NAG_FREE(irs);
NAG_FREE(isi);
NAG_FREE(isz);
NAG_FREE(ixs);
NAG_FREE(nca);
NAG_FREE(nct);

return exit_status;
}
```