EndErfc.cpp

Go to the documentation of this file.

// 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 +
//----------------------------------------------------------------------
// Includes
//----------------------------------------------------------------------
#include "MantidCurveFitting/Functions/EndErfc.h"
#include "MantidAPI/FunctionFactory.h"
#include <cmath>
#include <gsl/gsl_sf_erf.h>
 
namespace Mantid::CurveFitting::Functions {
 
using namespace CurveFitting;
 
using namespace Kernel;
 
using namespace API;
 
DECLARE_FUNCTION(EndErfc)
 
void EndErfc::init() {
  declareParameter("A", 2000.0, "Half value at minus infinity minus half value at plus infinity");
  declareParameter("B", 50.0, "Mid x value");
  declareParameter("C", 6.0, "Width parameter");
  declareParameter("D", 0.0, "Minimum value - must not be negative");
}
 
void EndErfc::function1D(double *out, const double *xValues, const size_t nData) const {
  const double gA = getParameter("A");
  const double gB = getParameter("B");
  const double gC = getParameter("C");
  const double gD = getParameter("D");
 
  for (size_t i = 0; i < nData; i++) {
    double x = xValues[i];
    out[i] = gA * gsl_sf_erfc((gB - x) / gC) + gD;
  }
 
  if (gA < 0) {
    for (size_t i = 0; i < nData; i++) {
      out[i] = -2 * gA;
    }
  }
}
 
void EndErfc::setActiveParameter(size_t i, double value) {
  size_t j = i;
 
  if (parameterName(j) == "D" && value < 0.0)
    setParameter(j, 0.0, false); // Don't let D become negative
  else
    setParameter(j, value, false);
}
 
} // namespace Mantid::CurveFitting::Functions