double SQuIDS::GetExpectationValueD(const SU_vector& op, unsigned int nrh, double xi,
SQuIDS::expectationValueDBuffer& buf) const{
//find bracketing state entries
auto xit=std::lower_bound(x.begin(),x.end(),xi);
if(xit==x.end())
throw std::runtime_error("SQUIDS::GetExpectationValueD : x value not in the array.");
if(xit!=x.begin())
xit--;
size_t xid=std::distance(x.begin(),xit);
//linearly interpolate between the two states
double f2=((xi-x[xid])/(x[xid+1]-x[xid]));
double f1=1-f2;
buf.state =f1*state[xid].rho[nrh];
buf.state+=f2*state[xid+1].rho[nrh];
//compute the evolved operator
buf.op=op.Evolve(H0(xi,nrh),t-t_ini);
//apply operator to state
return buf.state*buf.op;
}
double SQuIDS::GetExpectationValueD(const SU_vector& op, unsigned int nrh, double xi,
SQuIDS::expectationValueDBuffer& buf,
double scale, std::vector<bool>& avr) const{
//find bracketing state entries
auto xit=std::lower_bound(x.begin(),x.end(),xi);
if(xit==x.end())
throw std::runtime_error("SQUIDS::GetExpectationValueD : x value not in the array.");
if(xit!=x.begin())
xit--;
size_t xid=std::distance(x.begin(),xit);
//linearly interpolate between the two states
double f2=((xi-x[xid])/(x[xid+1]-x[xid]));
double f1=1-f2;
buf.state =f1*state[xid].rho[nrh];
buf.state+=f2*state[xid+1].rho[nrh];
//compute the evolved operator
std::unique_ptr<double[]> evol_buf(new double[H0(xi,nrh).GetEvolveBufferSize()]);
H0(xi,nrh).PrepareEvolve(evol_buf.get(),t-t_ini,scale,avr);
buf.op=op.Evolve(evol_buf.get());
//apply operator to state
return (buf.op*state[xid].rho[nrh])*f1 + (buf.op*state[xid+1].rho[nrh])*f2;
//return buf.state*buf.op;
}
double SQuIDS::GetExpectationValue(SU_vector op, unsigned int nrh, unsigned int i, double scale, std::vector<bool>& avr) const {
SU_vector h0=H0(x[i],nrh);
std::unique_ptr<double[]> evol_buf(new double[h0.GetEvolveBufferSize()]);
h0.PrepareEvolve(evol_buf.get(),t-t_ini,scale,avr);
return state[i].rho[nrh]*op.Evolve(evol_buf.get());
}
double SQuIDS::GetExpectationValue(SU_vector op, unsigned int nrh, unsigned int i) const{
SU_vector h0=H0(x[i],nrh);
return state[i].rho[nrh]*op.Evolve(h0,t-t_ini);
}