interpolate_CF4()

template<typename T >

void cntr::interpolate_CF4	(	int	tstp,
		cntr::function< T > &	H,
		cdmatrix &	Hinte1,
		cdmatrix &	Hinte2,
		int	kt,
		bool	fixHam = false
	)

Interpolation for the forth order propagator

Purpose

Interpolates \(H(t - dt + dt*c1)\) and \(H(t - dt + dt*c2)\), where

\(c1 = 1/2 - \sqrt(3)/6\) \(c2 = 1/2 + \sqrt(3)/6\) from \(H(t+dt)\), \(H(t)\), \(H(t-dt)\) where \(H(t+dt)\) is obtained from the extrapolation if not yet known. If fixham=true we assume that the hamiltonian is known for all times and there is no extrapolation

Parameters

tstp	timestep at which propagator is calculated
H	Time dependent Hamiltonian
Hinte1	Interpolated Hamiltonian at c1
Hinte2	Interpolated Hamiltonian at c2
kt	Order of integrator used for extrapolation and interpolation
fixHam	Hamiltonian is known for all times and no extrapolation is needed for the predictor/corrector

Definition at line 698 of file cntr_equilibrium_impl.hpp.

References integration::I< double >(), and cntr::function< T >::size1_.

Referenced by propagator_exp().

                                                                                                            {
    int size=H.size1_;
    cdmatrix tmp(size,size);
    int ktextrap=(tstp<=kt ? tstp : kt);
    int n1=(tstp<=kt ? kt : tstp);
    // Extrapolate to get H(t)
    if(!fixHam && tstp>kt){
        extrapolate_timestep(tstp-1,H,integration::I<double>(ktextrap));
    }
    Hinte1=interpolation(n1,(tstp-0.5-sqrt(3)/6.0),H,integration::I<double>(kt)); //ktextrap+1 since we added one more point
    Hinte2=interpolation(n1,(tstp-0.5+sqrt(3)/6.0),H,integration::I<double>(kt)); //ktextrap+1 since we added one more point

}

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