NAG Library Manual, Mark 27.3
```/* nag_mv_discrim_group (g03dcc) Example Program.
*
* Copyright 2021 Numerical Algorithms Group.
*
* Mark 27.3, 2021.
*
*/

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

#define ATI(I, J) ati[(I)*tdati + J]
#define P(I, J) p[(I)*tdp + J]
#define X(I, J) x[(I)*tdx + J]

int main(void) {
Integer exit_status = 0, i, *iag = 0, *ing = 0, *isx = 0, j, m, n, ng,
*nig = 0, nobs;
Integer nvar, tdati, tdgmean, tdp, tdx;
double *ati = 0, *det = 0, df, *gc = 0, *gmean = 0, *p = 0;
double *prior = 0, sig, stat, *wt = 0, *wtptr = 0, *x = 0;
char nag_enum_arg[40];
Nag_Boolean atiq = Nag_TRUE, weight;
Nag_DiscrimMethod type;
Nag_GroupCovars equal;
NagError fail;

INIT_FAIL(fail);

printf("nag_mv_discrim_group (g03dcc) Example Program Results\n\n");

/* Skip headings in data file */
scanf("%*[^\n]");
scanf("%" NAG_IFMT "", &n);
scanf("%" NAG_IFMT "", &m);
scanf("%" NAG_IFMT "", &nvar);
scanf("%" NAG_IFMT "", &ng);
scanf("%39s", nag_enum_arg);
/* nag_enum_name_to_value (x04nac).
* Converts NAG enum member name to value
*/
weight = (Nag_Boolean)nag_enum_name_to_value(nag_enum_arg);

if (n >= 1 && nvar >= 1 && m >= nvar && ng >= 2) {
if (!(det = NAG_ALLOC(ng, double)) ||
!(gc = NAG_ALLOC((ng + 1) * nvar * (nvar + 1) / 2, double)) ||
!(gmean = NAG_ALLOC((ng) * (nvar), double)) ||
!(prior = NAG_ALLOC(ng, double)) || !(wt = NAG_ALLOC(n, double)) ||
!(x = NAG_ALLOC((n) * (m), double)) || !(ing = NAG_ALLOC(n, Integer)) ||
!(isx = NAG_ALLOC(m, Integer)) || !(nig = NAG_ALLOC(ng, Integer))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
tdgmean = nvar;
tdx = m;
} else {
printf("Invalid n or nvar or ng.\n");
exit_status = 1;
return exit_status;
}
if (weight) {
for (i = 0; i < n; ++i) {
for (j = 0; j < m; ++j)
scanf("%lf", &X(i, j));
scanf("%" NAG_IFMT "", &ing[i]);
scanf("%lf", &wt[i]);
}
wtptr = wt;
} else {
for (i = 0; i < n; ++i) {
for (j = 0; j < m; ++j)
scanf("%lf", &X(i, j));
scanf("%" NAG_IFMT "", &ing[i]);
}
}
for (j = 0; j < m; ++j)
scanf("%" NAG_IFMT "", &isx[j]);

/* nag_mv_discrim (g03dac).
* Test for equality of within-group covariance matrices
*/
nag_mv_discrim(n, m, x, tdx, isx, nvar, ing, ng, wtptr, nig, gmean, tdgmean,
det, gc, &stat, &df, &sig, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_mv_discrim (g03dac).\n%s\n", fail.message);
exit_status = 1;
goto END;
}
scanf("%" NAG_IFMT "", &nobs);
scanf("%39s", nag_enum_arg);
equal = (Nag_GroupCovars)nag_enum_name_to_value(nag_enum_arg);
scanf("%39s", nag_enum_arg);
type = (Nag_DiscrimMethod)nag_enum_name_to_value(nag_enum_arg);
if (nobs >= 1) {
if (!(ati = NAG_ALLOC((nobs) * (ng), double)) ||
!(p = NAG_ALLOC((nobs) * (ng), double)) ||
!(iag = NAG_ALLOC(nobs, Integer))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
tdati = ng;
tdp = ng;
for (i = 0; i < nobs; ++i) {
for (j = 0; j < m; ++j) {
scanf("%lf", &X(i, j));
}
}

/* nag_mv_discrim_group (g03dcc).
* Allocates observations to groups, following
* nag_mv_discrim (g03dac)
*/
nag_mv_discrim_group(type, equal, Nag_EqualPrior, nvar, ng, nig, gmean,
tdgmean, gc, det, nobs, m, isx, x, tdx, prior, p, tdp,
iag, atiq, ati, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_mv_discrim_group (g03dcc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

printf("\n");
printf("    Obs       Posterior        Allocated ");
printf("      Atypicality ");
printf("\n");
printf("              probabilities    to group      index ");
printf("\n");
printf("\n");
for (i = 0; i < nobs; ++i) {
printf(" %6" NAG_IFMT "     ", i + 1);
for (j = 0; j < ng; ++j) {
printf("%6.3f", P(i, j));
}
printf("  %6" NAG_IFMT "    ", iag[i]);
for (j = 0; j < ng; ++j) {
printf("%6.3f", ATI(i, j));
}
printf("\n");
}
}

END:
NAG_FREE(ati);
NAG_FREE(det);
NAG_FREE(gc);
NAG_FREE(gmean);
NAG_FREE(p);
NAG_FREE(prior);
NAG_FREE(wt);
NAG_FREE(x);
NAG_FREE(iag);
NAG_FREE(ing);
NAG_FREE(isx);
NAG_FREE(nig);
return exit_status;
}
```