Convolution.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 "MantidAPI/CompositeFunction.h"
#include "MantidCurveFitting/DllConfig.h"
#include <cmath>
#include <memory>
#include <vector>
 
namespace Mantid {
namespace CurveFitting {
namespace Functions {
class MANTID_CURVEFITTING_DLL Convolution : public API::CompositeFunction {
public:
  class HalfComplex {
    size_t m_size;  
    double *m_data; 
    bool m_even;    
  public:
    HalfComplex(double *data, const size_t &n) : m_size(n / 2 + 1), m_data(data), m_even(n / 2 * 2 == n) {}
    size_t size() const { return m_size; }
    double real(size_t i) const {
      if (i >= m_size)
        return 0.;
      if (i == 0)
        return m_data[0];
      return m_data[2 * i - 1];
    }
    double imag(size_t i) const {
      if (i >= m_size)
        return 0.;
      if (i == 0)
        return 0;
      if (m_even && i == m_size - 1)
        return 0;
      return m_data[2 * i];
    }
    void set(size_t i, const double &re, const double &im) {
      if (i >= m_size)
        return;
      if (i == 0) // this is purely real
      {
        m_data[0] = re;
      } else if (m_even && i == m_size - 1) // this is also purely real
      {
        m_data[2 * i - 1] = re;
      } else {
        m_data[2 * i - 1] = re;
        m_data[2 * i] = im;
      }
    }
  };
 
  Convolution();
 
  std::string name() const override { return "Convolution"; }
  const std::string category() const override { return "General"; }
  void function(const API::FunctionDomain &domain, API::FunctionValues &values) const override;
  void functionFFTMode(const API::FunctionDomain &domain, API::FunctionValues &values) const;
  void functionDirectMode(const API::FunctionDomain &domain, API::FunctionValues &values) const;
  void functionDeriv(const API::FunctionDomain &domain, API::Jacobian &jacobian) override;
 
  void setAttribute(const std::string &attName, const Attribute &) override;
 
  size_t addFunction(API::IFunction_sptr f) override;
  void setUpForFit() override;
 
  void refreshResolution() const;
 
protected:
  void init() override;
 
private:
  mutable std::vector<double> m_resolution;
  void innerFunctionsAre1D() const;
};
 
} // namespace Functions
} // namespace CurveFitting
} // namespace Mantid