FlatBackground.cpp

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// Mantid Repository : https://github.com/mantidproject/mantid
//
// Copyright © 2018 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 +
#include "MantidCurveFitting/Functions/FlatBackground.h"
#include "MantidAPI/FunctionFactory.h"
#include "MantidKernel/System.h"
 
using namespace Mantid::Kernel;
 
using namespace Mantid::API;
 
namespace Mantid::CurveFitting::Functions {
 
using namespace CurveFitting;
DECLARE_FUNCTION(FlatBackground)
 
 
std::string FlatBackground::name() const { return "FlatBackground"; }
 
void FlatBackground::init() { declareParameter("A0", 0.0, "coefficient for linear term"); }
 
void FlatBackground::function1D(double *out, const double *xValues, const size_t nData) const {
  UNUSED_ARG(xValues);
 
  const double a0 = getParameter("A0");
 
  for (size_t i = 0; i < nData; i++) {
    out[i] = a0;
  }
}
 
void FlatBackground::functionDeriv1D(API::Jacobian *out, const double *xValues, const size_t nData) {
  UNUSED_ARG(xValues);
 
  for (size_t i = 0; i < nData; i++) {
    out->set(i, 0, 1);
  }
}
 
void FlatBackground::histogram1D(double *out, double left, const double *right, const size_t nBins) const {
 
  const double a0 = getParameter("A0");
 
  double cLeft = a0 * left;
  for (size_t i = 0; i < nBins; ++i) {
    double cRight = a0 * right[i];
    out[i] = cRight - cLeft;
    cLeft = cRight;
  }
}
 
void FlatBackground::histogramDerivative1D(Jacobian *jacobian, double left, const double *right,
                                           const size_t nBins) const {
 
  double xl = left;
  for (size_t i = 0; i < nBins; ++i) {
    double xr = right[i];
    jacobian->set(i, 0, xr - xl);
    xl = xr;
  }
}
 
} // namespace Mantid::CurveFitting::Functions