add numerical recipes library

lib/nr/ansi/examples/xeclazz.c

@@ -0,0 +1,45 @@
+
+/* Driver for routine eclazz */
+
+#include <stdio.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define N 15
+
+int equiv(int i,int j)
+{
+	return (i % 4) == (j % 4);
+}
+
+int main(void)
+{
+	int i,j,k,lclas=0,nclass,*nf,*nflag,*nsav;
+
+	nf=ivector(1,N);
+	nflag=ivector(1,N);
+	nsav=ivector(1,N);
+	eclazz(nf,N,equiv);
+	for (i=1;i<=N;i++) nflag[i]=1;
+	printf("\nNumbers from 1-%d divided according to\n",N);
+	printf("their value modulo 4:\n");
+	for (i=1;i<=N;i++) {
+		nclass=nf[i];
+		if (nflag[nclass]) {
+			nflag[nclass]=0;
+			lclas++;
+			k=0;
+			for (j=i;j<=N;j++)
+				if (nf[j] == nf[i]) nsav[++k]=j;
+			printf("Class %2d:      ",lclas);
+			for (j=1;j<=k;j++) printf("%3d",nsav[j]);
+			printf("\n");
+		}
+	}
+	free_ivector(nsav,1,N);
+	free_ivector(nflag,1,N);
+	free_ivector(nf,1,N);
+	return 0;
+}
+#undef NRANSI