add CrosscorrelationModels

Sample/Interface/CrosscorrelationModels.cpp

+//  ************************************************************************************************
+//
+//  BornAgain: simulate and fit reflection and scattering
+//
+//! @file      Sample/Interface/CrosscorrelationModels.cpp
+//! @brief     Implement CrossCorrModel classes.
+//!
+//! @homepage  http://www.bornagainproject.org
+//! @license   GNU General Public License v3 or higher (see COPYING)
+//! @copyright Forschungszentrum Jülich GmbH 2024
+//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
+//
+//  ************************************************************************************************
+
+#include "Sample/Interface/CrosscorrelationModels.h"
+#include <cmath>
+
+FixedDepthCrosscorrelation::FixedDepthCrosscorrelation(double cross_corr_depth)
+    : m_cross_corr_length(cross_corr_depth)
+{
+    validateOrThrow();
+}
+
+FixedDepthCrosscorrelation* FixedDepthCrosscorrelation::clone() const
+{
+    return new FixedDepthCrosscorrelation(m_cross_corr_length);
+}
+
+std::string FixedDepthCrosscorrelation::validate() const
+{
+    std::vector<std::string> errs;
+    requestGe0(errs, m_cross_corr_length, "crossCorrLength");
+    if (!errs.empty())
+        return jointError(errs);
+    m_validated = true;
+    return "";
+}
+
+double FixedDepthCrosscorrelation::replicationFactor(double thickness) const
+{
+    if (m_cross_corr_length == 0)
+        return 0;
+
+    return std::exp(-std::abs(thickness) / m_cross_corr_length);
+}

Sample/Interface/CrosscorrelationModels.h

+//  ************************************************************************************************
+//
+//  BornAgain: simulate and fit reflection and scattering
+//
+//! @file      Sample/Interface/CrosscorrelationModels.h
+//! @brief     Define CrosscorrelationModel classes.
+//!
+//! @homepage  http://www.bornagainproject.org
+//! @license   GNU General Public License v3 or higher (see COPYING)
+//! @copyright Forschungszentrum Jülich GmbH 2024
+//! @authors   Scientific Computing Group at MLZ (see CITATION, AUTHORS)
+//
+//  ************************************************************************************************
+
+#ifndef BORNAGAIN_SAMPLE_INTERFACE_CROSSCORRELATIONMODELS_H
+#define BORNAGAIN_SAMPLE_INTERFACE_CROSSCORRELATIONMODELS_H
+
+#include "Base/Type/ICloneable.h"
+#include "Param/Node/INode.h"
+#include <heinz/Vectors3D.h>
+
+//! Base class for cross-correlation function models.
+class CrosscorrelationModel : public ICloneable, public INode {
+public:
+    CrosscorrelationModel* clone() const override = 0;
+    virtual double crossCorrLength(const R3& k) const = 0;
+    virtual double replicationFactor(double thickness) const = 0;
+};
+
+//! The crosscorrelation factor depends on the distance between interfaces and does not depend
+//! on the spatial frequency.
+class FixedDepthCrosscorrelation : public CrosscorrelationModel {
+public:
+    FixedDepthCrosscorrelation(double cross_corr_depth = 0);
+    FixedDepthCrosscorrelation* clone() const override;
+    std::string className() const override { return "FixedDepthCrosscorrelation"; }
+    std::string validate() const override;
+    double crossCorrLength(const R3&) const override { return m_cross_corr_length; }
+    double replicationFactor(double thickness) const override;
+
+private:
+    double m_cross_corr_length = 0;
+};
+
+#endif // BORNAGAIN_SAMPLE_INTERFACE_CROSSCORRELATIONMODELS_H