NAG Library Manual, Mark 29
```/* nag_mv_cluster_hier (g03ecc) Example Program.
*
* Copyright 2023 Numerical Algorithms Group.
*
* Mark 29.0, 2023.
*
*/

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

#define X(I, J) x[(I)*tdx + J]
int main(void) {
Integer exit_status = 0, i, j, m, n, nsym, tdx;
Integer *ilc = 0, *iord = 0, *isx = 0, *iuc = 0;
char **c = 0, name[40][2];
double dmin_, dstep, ydist;
double *cd = 0, *d = 0, *dord = 0, *s = 0, *x = 0;
char nag_enum_arg[40];
Nag_ClusterMethod method;
Nag_DistanceType dist;
Nag_MatUpdate update;
Nag_VarScaleType scale;
NagError fail;

INIT_FAIL(fail);

printf("nag_mv_cluster_hier (g03ecc) Example Program "
"Results\n\n");

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

if (n >= 2 && m >= 1) {
if (!(cd = NAG_ALLOC(n - 1, double)) ||
!(d = NAG_ALLOC(n * (n - 1) / 2, double)) ||
!(dord = NAG_ALLOC(n, double)) || !(s = NAG_ALLOC(m, double)) ||
!(x = NAG_ALLOC(n * m, double)) || !(ilc = NAG_ALLOC(n - 1, Integer)) ||
!(iord = NAG_ALLOC(n, Integer)) || !(isx = NAG_ALLOC(m, Integer)) ||
!(iuc = NAG_ALLOC(n - 1, Integer))) {
printf("Allocation failure\n");
exit_status = -1;
goto END;
}
tdx = m;
} else {
printf("Invalid n or m.\n");
exit_status = 1;
return exit_status;
}
scanf("%39s", nag_enum_arg);
/* nag_enum_name_to_value (x04nac).
* Converts NAG enum member name to value
*/
method = (Nag_ClusterMethod)nag_enum_name_to_value(nag_enum_arg);
scanf("%39s", nag_enum_arg);
update = (Nag_MatUpdate)nag_enum_name_to_value(nag_enum_arg);
scanf("%39s", nag_enum_arg);
dist = (Nag_DistanceType)nag_enum_name_to_value(nag_enum_arg);
scanf("%39s", nag_enum_arg);
scale = (Nag_VarScaleType)nag_enum_name_to_value(nag_enum_arg);

for (j = 0; j < n; ++j) {
for (i = 0; i < m; ++i)
scanf("%lf", &X(j, i));
scanf("%1s", name[j]);
}
for (i = 0; i < m; ++i)
scanf("%" NAG_IFMT "", &isx[i]);
for (i = 0; i < m; ++i)
scanf("%lf", &s[i]);

/* Compute the distance matrix */
/* nag_mv_distance_mat (g03eac).
* Compute distance (dissimilarity) matrix
*/
nag_mv_distance_mat(update, dist, scale, n, m, x, tdx, isx, s, d, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_mv_distance_mat (g03eac).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

/* Perform clustering */
/* nag_mv_cluster_hier (g03ecc).
* Hierarchical cluster analysis
*/
nag_mv_cluster_hier(method, n, d, ilc, iuc, cd, iord, dord, &fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_mv_cluster_hier (g03ecc).\n%s\n", fail.message);
exit_status = 1;
goto END;
}

printf("\n   Distance   Clusters Joined\n\n");
for (i = 1; i <= n - 1; ++i)
printf("%10.3f     %3s%3s\n", cd[i - 1], name[ilc[i - 1] - 1],
name[iuc[i - 1] - 1]);

/* Produce dendrogram */
nsym = 20;
dmin_ = 0.0;
dstep = cd[n - 2] / (double)nsym;
/* nag_mv_cluster_hier_dendrogram (g03ehc).
* Construct dendrogram following
* nag_mv_cluster_hier (g03ecc)
*/
nag_mv_cluster_hier_dendrogram(Nag_DendSouth, n, dord, dmin_, dstep, nsym, &c,
&fail);
if (fail.code != NE_NOERROR) {
printf("Error from nag_mv_cluster_hier_dendrogram (g03ehc).\n%s\n",
fail.message);
exit_status = 1;
goto END;
}
printf("\n");
printf("Dendrogram ");
printf("\n");
printf("\n");
ydist = cd[n - 2];
for (i = 0; i < nsym; ++i) {
if ((i + 1) % 3 == 1) {
printf("%10.3f%6s", ydist, "");
printf("%s", c[i]);
printf("\n");
} else {
printf("%16s%s", "", c[i]);
printf("\n");
}
ydist -= dstep;
}
printf("\n");
printf("%14s", "");
for (i = 0; i < n; ++i) {
printf("%3s", name[iord[i] - 1]);
}
printf("\n");
/* nag_mv_dend_free (g03xzc).
* Frees memory allocated to the dendrogram array in
* nag_mv_cluster_hier_dendrogram (g03ehc)
*/
nag_mv_dend_free(&c);

END:
NAG_FREE(cd);
NAG_FREE(d);
NAG_FREE(dord);
NAG_FREE(s);
NAG_FREE(x);
NAG_FREE(ilc);
NAG_FREE(iord);
NAG_FREE(isx);
NAG_FREE(iuc);

return exit_status;
}
```