temporal_sampler_gauss.h

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/*****************************************************************************
* Multiscale Universal Interface Code Coupling Library                       *
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* Copyright (C) 2019 Y. H. Tang, S. Kudo, X. Bian, Z. Li, G. E. Karniadakis  *
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#ifndef MUI_TEMPORAL_SAMPLER_GAUSS_H_
#define MUI_TEMPORAL_SAMPLER_GAUSS_H_
 
#include "../../general/util.h"
#include "../../config.h"
 
namespace mui {
 
template<typename CONFIG=default_config> class temporal_sampler_gauss {
public:
    using REAL          = typename CONFIG::REAL;
    using INT           = typename CONFIG::INT;
    using time_type     = typename CONFIG::time_type;
    using iterator_type = typename CONFIG::iterator_type;
    
    temporal_sampler_gauss( time_type cutoff, REAL sigma ) {
        sigma_  = sigma;
        cutoff_ = cutoff;
    }
 
    //- Filter based on single time value
    template<typename TYPE>
    TYPE filter( time_type focus, const std::vector<std::pair<std::pair<time_type,iterator_type>, TYPE> > &points ) const {
        REAL wsum = REAL(0);
        TYPE vsum = TYPE(0);
        for( auto i: points ) {
            time_type dt = std::abs(i.first.first - focus);
            if ( dt < cutoff_ ) {
                REAL w = pow( 2*PI*sigma_, -0.5 ) * exp( -0.5 * dt * dt / sigma_ );
                vsum += i.second * w;
                wsum += w;
            }
        }
        return ( wsum > std::numeric_limits<REAL>::epsilon() ) ? ( vsum / wsum ) : TYPE(0);
    }
 
    //- Filter based on two time values
    template<typename TYPE>
    TYPE filter( std::pair<time_type,iterator_type> focus, const std::vector<std::pair<std::pair<time_type,iterator_type>, TYPE> > &points ) const {
        REAL wsum = REAL(0);
        TYPE vsum = TYPE(0);
        for( auto i: points ) {
            time_type dt1 = std::abs(i.first.first - focus.first);
            if ( dt1 < cutoff_ ) {
                REAL w = pow( 2*PI*sigma_, -0.5 ) * exp( -0.5 * dt1 * dt1 / sigma_ );
                vsum += i.second * w;
                wsum += w;
            }
        }
        return ( wsum > std::numeric_limits<REAL>::epsilon() ) ? ( vsum / wsum ) : TYPE(0);
    }
 
    time_type get_upper_bound( time_type focus ) const {
        return focus + cutoff_;
    }
 
    time_type get_lower_bound( time_type focus ) const {
        return focus - cutoff_;
    }
 
    time_type tolerance() const {
        return time_type(0);
    }
 
protected:
    time_type cutoff_;
    REAL sigma_;
};
 
}
 
#endif /* MUI_TEMPORAL_SAMPLER_GAUSS_H_ */