xcorrel.c

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/* 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