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/*
* geometry.h
*
* Geometry of diffraction
*
* Copyright © 2013-2021 Deutsches Elektronen-Synchrotron DESY,
* a research centre of the Helmholtz Association.
* Copyright © 2012 Richard Kirian
*
* Authors:
* 2010-2021 Thomas White <taw@physics.org>
* 2012 Richard Kirian
*
* This file is part of CrystFEL.
*
* CrystFEL is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* CrystFEL is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with CrystFEL. If not, see <http://www.gnu.org/licenses/>.
*
*/
#ifndef GEOMETRY_H
#define GEOMETRY_H
#include "reflist.h"
#include "cell.h"
#include "crystal.h"
#include "detgeom.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* \file geometry.h
* Geometry of diffraction
*
* This contains the prediction and partiality calculation functions.
*/
/**
* A PartialityModel describes a geometrical model which can be used to
* calculate spot partialities and Lorentz correction factors.
**/
typedef enum {
PMODEL_UNITY, /**< Set all partialities and Lorentz factors to 1. */
PMODEL_XSPHERE, /**< Flat sphere model with super-Gaussian spectrum */
PMODEL_OFFSET, /**< Ewald offset model for monochromatic beam */
PMODEL_RANDOM, /**< Randomly assigned partialities */
PMODEL_GGPM /**< Generalised gaussian prediction model */
} PartialityModel;
/**
* This structure represents the polarisation of the incident radiation
*/
struct polarisation
{
double fraction; /**< Polarisation fraction (0 to 1) */
double angle; /**< Angle of electron beam, radians, clockwise from
* horizontal when looking along beam */
int disable; /**< If set, don't even correct for the polarisation
* of the diffracted beam (1 - 0.5sin^2(2theta)) */
};
extern RefList *predict_to_res(Crystal *cryst, double max_res);
extern void calculate_partialities(Crystal *cryst, PartialityModel pmodel);
extern void update_predictions(Crystal *cryst);
extern struct polarisation parse_polarisation(const char *text);
extern void polarisation_correction(RefList *list, UnitCell *cell,
struct polarisation p);
extern double sphere_fraction(double rlow, double rhigh, double pr);
extern double gaussian_fraction(double rlow, double rhigh, double pr);
#ifdef __cplusplus
}
#endif
#endif /* GEOMETRY_H */
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