47 lines
963 B
C++
47 lines
963 B
C++
#include <cmath>
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#include "nr.h"
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using namespace std;
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void NR::realft(Vec_IO_DP &data, const int isign)
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{
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int i,i1,i2,i3,i4;
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DP c1=0.5,c2,h1r,h1i,h2r,h2i,wr,wi,wpr,wpi,wtemp,theta;
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int n=data.size();
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theta=3.141592653589793238/DP(n>>1);
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if (isign == 1) {
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c2 = -0.5;
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four1(data,1);
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} else {
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c2=0.5;
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theta = -theta;
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}
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wtemp=sin(0.5*theta);
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wpr = -2.0*wtemp*wtemp;
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wpi=sin(theta);
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wr=1.0+wpr;
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wi=wpi;
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for (i=1;i<(n>>2);i++) {
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i2=1+(i1=i+i);
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i4=1+(i3=n-i1);
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h1r=c1*(data[i1]+data[i3]);
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h1i=c1*(data[i2]-data[i4]);
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h2r= -c2*(data[i2]+data[i4]);
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h2i=c2*(data[i1]-data[i3]);
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data[i1]=h1r+wr*h2r-wi*h2i;
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data[i2]=h1i+wr*h2i+wi*h2r;
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data[i3]=h1r-wr*h2r+wi*h2i;
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data[i4]= -h1i+wr*h2i+wi*h2r;
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wr=(wtemp=wr)*wpr-wi*wpi+wr;
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wi=wi*wpr+wtemp*wpi+wi;
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}
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if (isign == 1) {
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data[0] = (h1r=data[0])+data[1];
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data[1] = h1r-data[1];
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} else {
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data[0]=c1*((h1r=data[0])+data[1]);
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data[1]=c1*(h1r-data[1]);
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four1(data,-1);
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}
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}
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