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InelasticDiffSphere.h
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/
InelasticDiffSphere.h
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// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2007 ISIS Rutherford Appleton Laboratory UKRI,
// NScD Oak Ridge National Laboratory, European Spallation Source,
// Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
// SPDX - License - Identifier: GPL - 3.0 +
#pragma once
#include "MantidAPI/MatrixWorkspace.h"
#include "MantidCurveFitting/Functions/DeltaFunction.h"
#include "MantidCurveFitting/Functions/FunctionQDepends.h"
namespace Mantid {
namespace CurveFitting {
namespace Functions {
/**
@author Jose Borreguero, NScD
@date 25/06/2016
*/
/// structure to hold info on Volino's coefficients
struct xnlc {
double x;
size_t n;
size_t l;
};
/// simple structure to hold a linear interpolation of factor J around its
/// numerical divergence point
struct linearJ {
double slope;
double intercept;
};
/**
* @brief Inelastic part of the DiffSphere function. Contains the 98
* Lorentzians.
*/
class MANTID_CURVEFITTING_DLL InelasticDiffSphere : public FunctionQDepends {
public:
InelasticDiffSphere();
/// overwrite IFunction base class methods
void init() override;
/// overwrite IFunction base class methods
std::string name() const override { return "InelasticDiffSphere"; }
/// overwrite IFunction base class methods
const std::string category() const override { return "QuasiElastic"; }
/// Calculate the (2l+1)*A_{n,l} coefficients for each Lorentzian
std::vector<double> LorentzianCoefficients(double a) const;
protected:
void function1D(double *out, const double *xValues, const size_t nData) const override;
private:
/// initialize the Xnl coefficients
void initXnlCoeff();
/// initialize the m_alpha coefficients
void initAlphaCoeff();
/// initialize the list of parameters for A_{n,l} linear interpolation around
/// the indeterminacy point
void initLinJlist();
/// Cache Q values from the workspace
void setWorkspace(std::shared_ptr<const API::Workspace> ws) override;
/// xnl coefficients
std::vector<xnlc> m_xnl;
/// certain coefficients invariant during fitting
std::vector<double> m_alpha;
/// maximum value of l in xnlist
size_t m_lmax;
/// linear interpolation zone around the numerical divergence of factor J
double m_divZone;
/// Plank's constant divided by \f$2\pi\f$, in units of meV*THz
double m_hbar;
/// list of linearized J values
std::vector<linearJ> m_linearJlist;
/// list of calculated Q values
std::vector<double> m_qValueCache;
}; // end of class InelasticDiffSphere
} // namespace Functions
} // namespace CurveFitting
} // namespace Mantid