int main(void)
{
FILE *f;
int i;
int iteration;
double x[2];
double xx[2];
double t, dt;
dt = 0.05;
iteration=1000;
x[0] = 1.0; // q
x[1] = 0.0; // p
f = fopen("trajectory_symp2.dat","w");
for (i=0; i<iteration; i++) {
t = i*dt;
fprintf(f,"%lf %lf %lf %le\n", t, x[0], x[1], Hamiltonian(t,x[0],x[1]));
Integrator(Symplectic2, t,dt,x,xx);
x[0] = xx[0];
x[1] = xx[1];
}
fclose(f);
return 0;
}
int Trajectory(double* X1, double* X2, double* Phi1, double* Phi2, double* K, int numProcs, int myID)
{
double* Eta = new double[TOT];
double* P = new double[TOT];
double* F = new double[TOT];
double* temK = new double[TOT];
double* temBuf = new double[TOT];
double t = sqrt(0.5);
int flag;
MPI_Generate(Eta, t, numProcs, myID);
M(Eta, Phi1, K, numProcs, myID);
MPI_Generate(Eta, t, numProcs, myID);
M(Eta, Phi2, K, numProcs, myID);
MPI_Setzero(X1, numProcs, myID);
MPI_Setzero(X2, numProcs, myID);
MPI_Generate(P, 1.0, numProcs, myID);
MPI_Assign(K, temK, numProcs, myID);
double hamStart = Hamiltonian(X1, X2, Phi1, Phi2, P, K, numProcs, myID);
flag = FermionForce(X1, X2, Phi1, Phi2, F, K, numProcs, myID);
if(!flag)
{
MPI_Assign(temK, K, numProcs, myID);
return 0;
}
MPI_Multiply(F, 0.5*dt, temBuf, numProcs, myID);
MPI_Add(P, temBuf, P, numProcs, myID);
for(int i = 0; i<(N_md-1); i++)
{
MPI_Multiply(P, dt, temBuf, numProcs, myID);
MPI_Add(K, temBuf, K, numProcs, myID);
flag = FermionForce(X1, X2, Phi1, Phi2, F, K, numProcs, myID);
if(!flag)
{
MPI_Assign(temK, K, numProcs, myID);
return 0;
}
MPI_Multiply(F, dt, temBuf, numProcs, myID);
MPI_Add(P, temBuf, P, numProcs, myID);
}
MPI_Multiply(P, dt, temBuf, numProcs, myID);
MPI_Add(K, temBuf, K, numProcs, myID);
flag = FermionForce(X1, X2, Phi1, Phi2, F, K, numProcs, myID);
if(!flag)
{
MPI_Assign(temK, K, numProcs, myID);
return 0;
}
MPI_Multiply(F, 0.5*dt, temBuf, numProcs, myID);
MPI_Add(P, temBuf, P, numProcs, myID);
double hamEnd = Hamiltonian(X1, X2, Phi1, Phi2, P, K, numProcs, myID);
double r = 0.0;
if(myID == ROOT)
{
random_device rd;
mt19937 generator(rd());
uniform_real_distribution<double> dis(0.0, 1.0);
r = dis(generator);
}
MPI_Bcast(&r, 1, MPI_DOUBLE, ROOT, MPI_COMM_WORLD);
double s = exp(hamStart-hamEnd);
if(myID == ROOT)
{
ofstream file_log("evolution.log", ios_base::app);
file_log<<"Hamiltoian: "<<hamStart<<" "<<hamEnd<<" "<<r<<" "<<s<<endl;
file_log.close();
}
delete [] Eta;
delete [] P;
delete [] F;
delete [] temK;
delete [] temBuf;
if(r<s)
{
return 1;
}
else
{
MPI_Assign(temK, K, numProcs, myID);
return 0;
}
}