add numerical recipes library

lib/nr/ansi/examples/xcorrel.c

@@ -0,0 +1,41 @@
+
+/* Driver for routine correl */
+
+#include <stdio.h>
+#define NRANSI
+#include "nr.h"
+#include "nrutil.h"
+
+#define N 64
+#define N2 (2*N)
+
+int main(void)
+{
+	unsigned long i,j;
+	float cmp,*data1,*data2,*ans;
+
+	data1=vector(1,N);
+	data2=vector(1,N);
+	ans=vector(1,N2);
+	for (i=1;i<=N;i++) {
+		if ((i > N/2-N/8) && (i < N/2+N/8))
+			data1[i]=1.0;
+		else
+			data1[i]=0.0;
+		data2[i]=data1[i];
+	}
+	correl(data1,data2,N,ans);
+	/* Calculate directly */
+	printf("%3s %14s %18s\n","n","CORREL","direct calc.");
+	for (i=0;i<=16;i++) {
+		cmp=0.0;
+		for (j=1;j<=N;j++)
+			cmp += data1[((i+j-1) % N)+1]*data2[j];
+		printf("%3ld %15.6f %15.6f\n",i,ans[i+1],cmp);
+	}
+	free_vector(ans,1,N2);
+	free_vector(data2,1,N);
+	free_vector(data1,1,N);
+	return 0;
+}
+#undef NRANSI