Implementation of material factory functions

Redmine: #1858

Core/Material/MaterialFactoryFuncs.cpp

+#include "MaterialFactoryFuncs.h"
+#include "RefractiveCoefMaterial.h"
+#include "WavelengthIndependentMaterial.h"
+
+Material RefractiveIndexMaterial(const std::string& name, complex_t refractive_index,
+                                 kvector_t magnetization)
+{
+    const double delta = 1.0 - refractive_index.real();
+    const double beta = refractive_index.imag();
+    std::unique_ptr<RefractiveCoefMaterial> mat_impl(
+        new RefractiveCoefMaterial(name, delta, beta, magnetization));
+    return Material(std::move(mat_impl));
+}
+
+Material RefractiveIndexMaterial(const std::string& name, double delta, double beta,
+                                 kvector_t magnetization)
+{
+    std::unique_ptr<RefractiveCoefMaterial> mat_impl(
+        new RefractiveCoefMaterial(name, delta, beta, magnetization));
+    return Material(std::move(mat_impl));
+}
+
+Material MaterialBySLD(const std::string& name, double sld, double abs_term,
+                       kvector_t magnetization)
+{
+    std::unique_ptr<WavelengthIndependentMaterial> mat_impl(
+        new WavelengthIndependentMaterial(name, sld, abs_term, magnetization));
+    return Material(std::move(mat_impl));
+}
+
+constexpr double basic_wavelength = 0.1798197; // nm, wavelength of 2200 m/s neutrons
+Material MaterialByAbsCX(const std::string& name, double sld, double abs_cx,
+                         kvector_t magnetization)
+{
+    std::unique_ptr<WavelengthIndependentMaterial> mat_impl(
+        new WavelengthIndependentMaterial(name, sld, abs_cx / basic_wavelength, magnetization));
+    return Material(std::move(mat_impl));
+}

Core/Material/MaterialFactoryFuncs.h

+// ************************************************************************** //
+//
+//  BornAgain: simulate and fit scattering at grazing incidence
+//
+//! @file      Core/Material/MaterialFactoryFuncs.h
+//! @brief     Defines factory functions for creating different flavors of materials.
+//!
+//! @homepage  http://www.bornagainproject.org
+//! @license   GNU General Public License v3 or higher (see COPYING)
+//! @copyright Forschungszentrum Jülich GmbH 2015
+//! @authors   Scientific Computing Group at MLZ Garching
+//! @authors   C. Durniak, M. Ganeva, G. Pospelov, W. Van Herck, J. Wuttke
+//
+// ************************************************************************** //
+
+#ifndef MATERIALFACTORYFUNCS_H_
+#define MATERIALFACTORYFUNCS_H_
+
+#include "Material.h"
+
+//! Constructs a material with _name_ and _refractive_index_.
+BA_CORE_API_ Material RefractiveIndexMaterial(const std::string& name, complex_t refractive_index,
+                                              kvector_t magnetization = kvector_t());
+
+//! Constructs a material with _name_ and refractive_index parameters
+//! \f$\delta\f$ and \f$\beta\f$ for refractive index \f$n = 1 - \delta + i \beta\f$.
+BA_CORE_API_ Material RefractiveIndexMaterial(const std::string& name, double delta, double beta,
+                                              kvector_t magnetization = kvector_t());
+
+//! Constructs a wavelength-independent material with given sld and absorptive term
+//! Absorptive term is wavelength-independent (normalized to a wavelength)
+//! and can be considered as inverse of imaginary part of complex scattering length density:
+//! \f$ SLD = (N b_{coh}, N \sigma_{abs}(\lambda_0) / \lambda_0) \f$
+//! Here \f$ N \f$ - material number density,
+//! \f$ b_{coh} \f$ - bound coherent scattering length
+//! \f$ \sigma_{abs}(\lambda_0) \f$ - absorption cross-section at \f$ \lambda_0 \f$ wavelength
+//! @param sld: scattering length density, \f$ nm^{-2} \f$
+//! @param abs_term: wavelength-independent absorptive term, \f$ nm^{-2} \f$
+BA_CORE_API_ Material MaterialBySLD(const std::string& name, double sld, double abs_term,
+                                    kvector_t magnetization = kvector_t());
+
+//! Constructs a wavelength-independent material with given sld and absorptive term
+//! As opposed to MaterialBySLD, absorptive term is the product of number density and
+//! absorptive cross-section \f$ \sigma_0 \f$ at \f$ \lambda = 1.798197\f$ Angstroms.
+//! The latter corresponds to 2200 m/s neutrons.
+//! @param sld: scattering length density, \f$ nm^{-2} \f$
+//! @param abs_cx: absorptive term at \f$ \lambda = 1.798197\f$ Angstroms, \f$ nm^{-1} \f$
+BA_CORE_API_ Material MaterialByAbsCX(const std::string& name, double sld, double abs_cx,
+                                      kvector_t magnetization = kvector_t());
+
+#endif /* MATERIALFACTORYFUNCS_H_ */