add numerical recipes library

lib/nr/ansi/examples/xigray.c

@@ -0,0 +1,31 @@
+
+/* Driver for routine igray */
+
+#include <stdio.h>
+#define NRANSI
+#include "nr.h"
+
+int main(void)
+{
+	unsigned long jp,n,ng,nmax,nmin,nni,nxor;
+
+	for (;;) {
+		printf("input nmin,nmax: \n");
+		if (scanf("%lu %lu",&nmin,&nmax) == EOF) break;
+		jp=(nmax-nmin)/11;
+		if (jp < 1) jp=1;
+		printf("n, Gray[n], Gray(Gray[n]), Gray[n] ^ Gray[n+1]\n");
+		for (n=nmin;n<=nmax;n++) {
+			ng=igray(n,1);
+			nni=igray(ng,-1);
+			if (nni != n) printf("WRONG ! AT %d %d %d\n",n,ng,nni);
+			if (!((n-nmin) % jp)) {
+					nxor=ng ^ igray(n+1,1);
+					printf("%lu %lu %lu %lu\n",n,ng,nni,nxor);
+			}
+		}
+	}
+	printf("Normal completion\n");
+	return 0;
+}
+#undef NRANSI