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;
 
class MANTID_CURVEFITTING_DLL BSpline : public BackgroundFunction {
public:
  BSpline();
  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;
 
  void setAttribute(const std::string &attName, const Attribute &) override;
  std::vector<std::string> getAttributeNames() const override;
 
  void resetParameters();
  void resetKnots();
  void resetValidators();
  [[nodiscard]] std::vector<double> calcUniformBreakPoints(const double startX, const double endX);
  void resetKnotVector(const std::vector<double> &breakPoints);
  size_t evaluateBasisFunctions(EigenVector &B, const double x, size_t currentBBase) const;
  void initialiseSpline(const std::vector<double> &breakPoints);
  size_t getSpanIndex(const double x, const size_t currentBBase, const bool clamped = true) const;
  [[nodiscard]] EigenMatrix evaluateBasisFnDerivatives(const double x, const size_t derivOrder) const;
 
  inline int getNBSplineCoefficients() { return getNBreakPoints() + getOrder() - 2; }
  inline int getNBreakPoints() const { return getAttribute("NBreak").asInt(); }
  inline int getNKnots() const { return getNBreakPoints() + getClampedKnots() * 2 - 2; }
  inline int getOrder() const { return getAttribute("Order").asInt(); }
  inline int getClampedKnots() const { return getDegree() + 1; }
  inline int getDegree() const { return getOrder() - 1; }
 
  Spline1D m_spline;
  std::vector<double> m_knots;
};
 
} // namespace Mantid::CurveFitting::Functions