54 lines
1.2 KiB
C++
54 lines
1.2 KiB
C++
#include <cmath>
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#include "nr.h"
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using namespace std;
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void NR::dftint(DP func(const DP), const DP a, const DP b, const DP w,
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DP &cosint, DP &sinint)
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{
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static int init=0;
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static DP (*funcold)(const DP);
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static DP aold = -1.e30,bold = -1.e30,delta;
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const int M=64,NDFT=1024,MPOL=6;
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const DP TWOPI=6.283185307179586476;
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int j,nn;
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DP c,cdft,cerr,corfac,corim,corre,en,s,sdft,serr;
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static Vec_DP data(NDFT),endpts(8);
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Vec_DP cpol(MPOL),spol(MPOL),xpol(MPOL);
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if (init != 1 || a != aold || b != bold || func != funcold) {
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init=1;
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aold=a;
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bold=b;
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funcold=func;
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delta=(b-a)/M;
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for (j=0;j<M+1;j++)
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data[j]=func(a+j*delta);
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for (j=M+1;j<NDFT;j++)
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data[j]=0.0;
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for (j=0;j<4;j++) {
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endpts[j]=data[j];
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endpts[j+4]=data[M-3+j];
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}
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realft(data,1);
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data[1]=0.0;
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}
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en=w*delta*NDFT/TWOPI+1.0;
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nn=MIN(MAX(int(en-0.5*MPOL+1.0),1),NDFT/2-MPOL+1);
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for (j=0;j<MPOL;j++,nn++) {
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cpol[j]=data[2*nn-2];
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spol[j]=data[2*nn-1];
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xpol[j]=nn;
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}
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polint(xpol,cpol,en,cdft,cerr);
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polint(xpol,spol,en,sdft,serr);
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dftcor(w,delta,a,b,endpts,corre,corim,corfac);
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cdft *= corfac;
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sdft *= corfac;
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cdft += corre;
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sdft += corim;
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c=delta*cos(w*a);
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s=delta*sin(w*a);
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cosint=c*cdft-s*sdft;
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sinint=s*cdft+c*sdft;
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}
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