VarianceFunctions.h

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// ************************************************************************** //
//
//  BornAgain: simulate and fit scattering at grazing incidence
//
//! @file      Device/Instrument/VarianceFunctions.h
//! @brief     Defines IVarianceFunction classes
//!
//! @homepage  http://www.bornagainproject.org
//! @license   GNU General Public License v3 or higher (see COPYING)
//! @copyright Forschungszentrum Jülich GmbH 2018
//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
//
// ************************************************************************** //
 
#ifndef BORNAGAIN_CORE_INSTRUMENT_VARIANCEFUNCTIONS_H
#define BORNAGAIN_CORE_INSTRUMENT_VARIANCEFUNCTIONS_H
 
//! Variance function interface.
//! @ingroup fitting_internal
 
class IVarianceFunction
{
public:
    IVarianceFunction();
    virtual ~IVarianceFunction();
    virtual IVarianceFunction* clone() const = 0;
    virtual double variance(double real_value, double simulated_value) const = 0;
 
    IVarianceFunction(const IVarianceFunction&) = delete;
    IVarianceFunction& operator=(const IVarianceFunction&) = delete;
};
 
//! Returns 1.0 as variance value
//! @ingroup fitting
 
class VarianceConstantFunction : public IVarianceFunction
{
public:
    VarianceConstantFunction* clone() const override;
    double variance(double, double) const override;
};
 
//! Returns max(sim, epsilon)
//! @ingroup fitting
 
class VarianceSimFunction : public IVarianceFunction
{
public:
    explicit VarianceSimFunction(double epsilon = 1.0);
    VarianceSimFunction* clone() const override;
    double variance(double exp, double sim) const override;
 
private:
    double m_epsilon;
};
 
#endif // BORNAGAIN_CORE_INSTRUMENT_VARIANCEFUNCTIONS_H