Created
April 5, 2014 17:31
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#include <iostream> | |
#include <complex> | |
#include <cmath> | |
#include <vector> | |
using namespace std; | |
using cplx=complex<double>; | |
template<typename T> | |
constexpr T pi(){ | |
return 3.141592653589793238463L; | |
} | |
enum FToption{ | |
IDFT=-1, | |
DFT=1 | |
}; | |
void FT_DataShift(vector<cplx> &data){ | |
int size=data.size(); | |
for(int i=0;i<size/2;i++){ | |
auto swap_tmp=data[i]; | |
data[i]=data[i+size/2]; | |
data[i+size/2]=swap_tmp; | |
} | |
} | |
void FourierTransform(vector<cplx> &data,FToption option){ | |
FT_DataShift(data); | |
int size=data.size(); | |
vector<cplx> buf(size); | |
if(option==IDFT){ | |
for(int i=0;i<size;i++){ | |
data[i]/=size; | |
} | |
} | |
for(int i=0;i<size;i++){ | |
for(int j=0;j<size;j++){ | |
buf[i]+=data[j]*exp(cplx(0,-2.0*pi<double>()*i*j/size*(int)option)); | |
} | |
} | |
for(int i=0;i<size;i++){ | |
data[i]=buf[i]; | |
} | |
FT_DataShift(data); | |
} | |
int main(){ | |
const int size=128; | |
vector<cplx> data(size); | |
int i=0; | |
for(int i=0;i<size;i++){ | |
data[i].imag(0); | |
if(i==size/2)data[i].real(255.0); | |
} | |
FourierTransform(data,DFT); | |
for(int i=0;i<size;i++){ | |
cout<<data[i]<<endl; | |
} | |
FourierTransform(data,IDFT); | |
for(int i=0;i<size;i++){ | |
cout<<data[i]<<endl; | |
} | |
} |
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