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