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BSpline.h
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BSpline.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
//----------------------------------------------------------------------
// Includes
//----------------------------------------------------------------------
#include "MantidCurveFitting/EigenMatrix.h"
#include "MantidCurveFitting/EigenVector.h"
#include "MantidCurveFitting/Functions/BackgroundFunction.h"
#include "MantidKernel/IValidator.h"
#include <memory>
#include <unsupported/Eigen/Splines>
namespace Mantid::CurveFitting::Functions {
typedef Eigen::Spline<double, 1, Eigen::Dynamic> Spline1D;
/**
A wrapper around Eigen functions implementing a B-spline.
This function can also calculate basis function derivatives.
*/
class MANTID_CURVEFITTING_DLL BSpline : public BackgroundFunction {
public:
/// Constructor
BSpline();
/// overwrite IFunction base class methods
std::string name() const override { return "BSpline"; }
const std::string category() const override { return "Background"; }
void function1D(double *out, const double *xValues, const size_t nData) const override;
void derivative1D(double *out, const double *xValues, size_t nData, const size_t order) const override;
/// Set a value to attribute attName
void setAttribute(const std::string &attName, const Attribute &) override;
/// Returns a list of attribute names
std::vector<std::string> getAttributeNames() const override;
/// Reset fitting parameters
void resetParameters();
/// Reset b-spline knots
void resetKnots();
/// Reset Function Attribute Validators
void resetValidators();
/// Populate a vector with a uniform set of break points
[[nodiscard]] std::vector<double> calcUniformBreakPoints(const double startX, const double endX);
/// Reset knot vector based upon break points
void resetKnotVector(const std::vector<double> &breakPoints);
/// evaluate non-zero basis functions, return which index to use as the base of the results vector.
size_t evaluateBasisFunctions(EigenVector &B, const double x, size_t currentBBase) const;
/// initialise the m_spline variable based on the knot vector and given a vector of breakpoints
void initialiseSpline(const std::vector<double> &breakPoints);
/// get the index of the span/interval which x is in
size_t getSpanIndex(const double x, const size_t currentBBase, const bool clamped = true) const;
/// Evaluate derivatives up to a specified order for each non-zero basis function
[[nodiscard]] EigenMatrix evaluateBasisFnDerivatives(const double x, const size_t derivOrder) const;
/// Get number of B-Spline coefficients
inline int getNBSplineCoefficients() { return getNBreakPoints() + getOrder() - 2; }
/// Get number of Break Points
inline int getNBreakPoints() const { return getAttribute("NBreak").asInt(); }
/// Get number of Knots
inline int getNKnots() const { return getNBreakPoints() + getClampedKnots() * 2 - 2; }
/// Get order of the spline, k
inline int getOrder() const { return getAttribute("Order").asInt(); }
/// Get number of knots required to clamp the spline closed
inline int getClampedKnots() const { return getDegree() + 1; }
/// Get the degree of constituent polynomial functions
inline int getDegree() const { return getOrder() - 1; }
/// Member variable for spline
Spline1D m_spline;
std::vector<double> m_knots;
};
} // namespace Mantid::CurveFitting::Functions