add numerical recipes library

lib/nr/ansi/recipes/eclass.c

@@ -0,0 +1,16 @@
+
+void eclass(int nf[], int n, int lista[], int listb[], int m)
+{
+	int l,k,j;
+
+	for (k=1;k<=n;k++) nf[k]=k;
+	for (l=1;l<=m;l++) {
+		j=lista[l];
+		while (nf[j] != j) j=nf[j];
+		k=listb[l];
+		while (nf[k] != k) k=nf[k];
+		if (j != k) nf[j]=k;
+	}
+	for (j=1;j<=n;j++)
+		while (nf[j] != nf[nf[j]]) nf[j]=nf[nf[j]];
+}