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_SAMPLER_GAUSS_H_
#define MUI_SAMPLER_GAUSS_H_
 
#include "../../general/util.h"
#include "../../config.h"
#include "../sampler.h"
 
namespace mui {
 
template<typename CONFIG=default_config, typename O_TP=typename CONFIG::REAL, typename I_TP=O_TP>
class sampler_gauss {
public:
    using OTYPE      = O_TP;
    using ITYPE      = I_TP;
    using REAL       = typename CONFIG::REAL;
    using INT        = typename CONFIG::INT;
    using point_type = typename CONFIG::point_type;
 
    sampler_gauss( REAL r_, REAL h_ ) : r(r_), h(h_), nh(std::pow(2*PI*h,-0.5*CONFIG::D)) {}
 
    template<template<typename,typename> class CONTAINER>
    inline OTYPE filter( point_type focus, const CONTAINER<ITYPE,CONFIG> &data_points ) const {
        REAL exp_val = -0.5/h;
        REAL r2 = r*r;
      REAL  wsum = 0;
        OTYPE vsum = 0;
        for( size_t i = 0 ; i < data_points.size() ; i++ ) {
            REAL d = normsq( focus - data_points[i].first );
            if ( d < r2 ) {
              REAL w = nh * std::exp( exp_val * d );
                vsum += data_points[i].second * w;
                wsum += w;
            }
        }
        if ( wsum ) return vsum / wsum;
        else return REAL(0.);
    }
 
    inline geometry::any_shape<CONFIG> support( point_type focus, REAL domain_mag ) const {
        return geometry::sphere<CONFIG>( focus, r );
    }
 
protected:
    REAL r;
    REAL h;
    REAL nh;
};
 
}
 
#endif /* MUI_SAMPLER_GAUSS_H_ */