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Mean_BEC_momentum_dist_nola.cpp
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Mean_BEC_momentum_dist_nola.cpp
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#include"fftw3.h"
#include<vector>
#include<iostream>
#include"headers/split_step.h"
#include"headers/bec.h"
#include<algorithm>
#include<functional>
#include<iterator>
#include<cmath>
#include<complex>
#include"headers/BEC_Groundstate.h"
#include <boost/numeric/ublas/matrix.hpp>
#include <boost/numeric/ublas/vector.hpp>
#include <boost/numeric/ublas/io.hpp>
using namespace std;
int main(int argc, char* argv[]){
typedef std::vector<double> Vector;
typedef std::vector<complex<double> > Cvector;
typedef boost::numeric::ublas::matrix<double> Matrix;
typedef complex<double> complex_type;
typedef fftw_complex complex_c_type;
typedef vector<complex<double> >::size_type size_t;
typedef complex<double> complex_type;
typedef fftw_complex complex_c_type;
double K = 0.1;
double g = 0.1;
double maxt = 20;
int period = 10000;
const double L = 10;
double mynorm= 0;
int N=1024;
const double deltat = 2.*pi/double(period);
const complex_type I(0,1);
double t=0;
int stepcounter=1;
//parsing command line
switch(argc){
case 1:
break;
case 2:
K=atof(argv[1]);
break;
case 3:
K=atof(argv[1]);
g=atof(argv[2]);
break;
case 4:
K=atof(argv[1]);
g=atof(argv[2]);
maxt=atof(argv[3]);
break;
case 5:
K=atof(argv[1]);
g=atof(argv[2]);
maxt=atof(argv[3]);
period = atoi(argv[4]);
break;
case 6:
K=atof(argv[1]);
g=atof(argv[2]);
maxt=atof(argv[3]);
period = atoi(argv[4]);
N=atoi(argv[5]);
break;
default:
break;
}
//finding Groundstate
Cvector data(N);
Cvector mom(N);
Cvector mean(N);
for(int i = 0; i<N; ++i){
double xpos = L*0.5-double(i)*L/double(N);
data[i]=1./sqrt(sqrt(pi) )*exp(-xpos*xpos/2.);
}
for(int i = 0; i<20000;++i){
data=split_step::S3imag(L, deltat, g, data, bec::Potential<double, false, true>() );
mynorm = L_2_norm(data.begin(), data.end(), L);
//cout<<mynorm<<endl;
transform(data.begin(), data.end(), data.begin(), bind2nd(divides<complex<double> >(), mynorm) );
}
//properly normalize the whole thing, so that we may use it with the propagator.
mynorm = L_2_norm(data.begin(), data.end(), L);
transform(data.begin(), data.end(), data.begin(), bind2nd(divides<complex<double> >(), mynorm) );
cout<<"System size"<<'\t'<<"Points"<<'\t'<<"Coupling"<<'\t'<<"deltat"<<'\t'<<"Kick strength"<<'\t'<<"Max time"<<'\t'<<"Period"<<endl;
cout<<L<<'\t'<<N<<'\t'<<g<<'\t'<<deltat<<'\t'<<K<<'\t'<<maxt<<'\t'<<period<<endl<<endl;
vector<complex_type> kick(N);
for (size_t i = 0; i<N; ++i) {
double xpos = L*0.5-double(i)*L/double(N);
kick[i]= exp(-I*K*sin(xpos));
}
transform(data.begin(), data.end(), kick.begin(), data.begin(), multiplies<complex_type>() );
for(;t<maxt; t+=deltat, ++stepcounter){
data=split_step::S3(L, deltat, g, data, bec::Potential<double, false, true>() );
mom=FourierTransform<fft::forward, fft::Estimate>(data);
transform(mom.begin(), mom.end(), mom.begin(), bind2nd(divides<complex<double> >(), double(period) ) );
transform(mean.begin(), mean.end(), mom.begin(), mean.begin(), plus<complex<double> >() );
if(!(stepcounter%period) ){
cout<<"& "<<"period: "<<period<<endl;
for(int i = 0; i<mean.size(); ++i){
int index = (i<mean.size()/2)?i+mean.size()/2:i-mean.size()/2;
cout<<norm(mean[index])<<endl;
mean[index]=0;
}
}
}
return 0;
}