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StaticKuboToyabeTimesExpDecay.cpp
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1// Mantid Repository : https://github.com/mantidproject/mantid
2//
3// Copyright © 2018 ISIS Rutherford Appleton Laboratory UKRI,
4// NScD Oak Ridge National Laboratory, European Spallation Source,
5// Institut Laue - Langevin & CSNS, Institute of High Energy Physics, CAS
6// SPDX - License - Identifier: GPL - 3.0 +
9#include <cmath>
10
12
13using namespace CurveFitting;
14
15using namespace Kernel;
16
17using namespace API;
18
19DECLARE_FUNCTION(StaticKuboToyabeTimesExpDecay)
20
22 declareParameter("A", 0.2, "Amplitude at time 0");
23 declareParameter("Delta", 0.2, "StaticKuboToyabe decay rate");
24 declareParameter("Lambda", 0.2, "Exponential decay rate");
25}
26
27void StaticKuboToyabeTimesExpDecay::function1D(double *out, const double *xValues, const size_t nData) const {
28 const double A = getParameter("A");
29 const double D = getParameter("Delta");
30 const double L = getParameter("Lambda");
31
32 const double C1 = 2.0 / 3;
33 const double C2 = 1.0 / 3;
34
35 for (size_t i = 0; i < nData; i++) {
36 double x = xValues[i];
37 double DXSquared = pow(D * x, 2);
38 out[i] = A * (exp(-DXSquared / 2) * (1 - DXSquared) * C1 + C2) * exp(-L * x);
39 }
40}
41
42} // namespace Mantid::CurveFitting::Functions
#define DECLARE_FUNCTION(classname)
Macro for declaring a new type of function to be used with the FunctionFactory.
double getParameter(size_t i) const override
Get i-th parameter.
void function1D(double *out, const double *xValues, const size_t nData) const override
Function you want to fit to.