#define NRANSI#include "nrutil.h"void correl(float data1[], float data2[], unsigned long n, float ans[]){	void realft(float data[], unsigned long n, int isign);	void twofft(float data1[], float data2[], float fft1[], float fft2[],		unsigned long n);	unsigned long no2,i;	float dum,*fft;	fft=vector(1,n<<1);	twofft(data1,data2,fft,ans,n);	no2=n>>1;	for (i=2;i<=n+2;i+=2) {		ans[i-1]=(fft[i-1]*(dum=ans[i-1])+fft[i]*ans[i])/no2;		ans[i]=(fft[i]*dum-fft[i-1]*ans[i])/no2;	}	ans[2]=ans[n+1];	realft(ans,n,-1);	free_vector(fft,1,n<<1);}#undef NRANSI