Justine Devin / gammalib

Commit f3cdb72c3b56ee5dc5019cdb9eef7fa91d6d6146

Authored by knodlseder
1 parent 68928c4a

initial version

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inst/cta/src/GCTASupport.cpp 0 → 100644
  View file @f3cdb72
  1 +/***************************************************************************
  2 + * GCTASupport.cpp - CTA support functions *
  3 + * ----------------------------------------------------------------------- *
  4 + * copyright (C) 2011 by Jurgen Knodlseder *
  5 + * ----------------------------------------------------------------------- *
  6 + * *
  7 + * This program is free software; you can redistribute it and/or modify *
  8 + * it under the terms of the GNU General Public License as published by *
  9 + * the Free Software Foundation; either version 2 of the License, or *
  10 + * (at your option) any later version. *
  11 + * *
  12 + ***************************************************************************/
  13 +/**
  14 + * @file GCTASupport.cpp
  15 + * @brief Implementation of support function used by CTA classes
  16 + * @author J. Knodlseder
  17 + */
  18 +
  19 +/* __ Includes ___________________________________________________________ */
  20 +#ifdef HAVE_CONFIG_H
  21 +#include <config.h>
  22 +#endif
  23 +#include "GCTASupport.hpp"
  24 +#include "GTools.hpp"
  25 +
  26 +/* __ Coding definitions _________________________________________________ */
  27 +
  28 +
  29 +/***********************************************************************//**
  30 + * @brief Returns length of circular arc within circular ROI
  31 + *
  32 + * @param[in] rad Circle radius in radians (<pi).
  33 + * @param[in] dist Circle centre distance to ROI centre (<pi).
  34 + * @param[in] cospsf Cosine of circle centre distance to ROI centre.
  35 + * @param[in] sindist Sinus of circle centre distance to ROI centre.
  36 + * @param[in] roi Radius of ROI in radians.
  37 + * @param[in] cosroi Cosine of ROI radius.
  38 + *
  39 + * This method returns the arclength in radians of a circle of radius 'rad'
  40 + * with a centre that is offset by 'dist' from the ROI centre, where the ROI
  41 + * radius is given by 'roi'. To speed-up computations, the cosines and sinus
  42 + * of 'roi' and 'psf' should be calculated by the client and be passed to
  43 + * the method.
  44 + ***************************************************************************/
  45 +double cta_roi_arclength(const double& rad, const double& dist,
  46 + const double& cosdist, const double& sindist,
  47 + const double& roi, const double& cosroi)
  48 +{
  49 + // Declare arclength
  50 + double arclength;
  51 +
  52 + // Handle special case that circle centre matches ROI centre
  53 + if (dist == 0.0) {
  54 + if (rad > roi) arclength = 0.0; // Circle outside ROI
  55 + else arclength = twopi; // Circle inside ROI
  56 + }
  57 +
  58 + // ... otherwise circle and ROI centres are not identical
  59 + else {
  60 +
  61 + // Handle special case that we evaluate exactly at the circle
  62 + // centre. In this case we have in fact a point, and if this point
  63 + // falls within the ROI it has a formal arclength of 2pi.
  64 + //
  65 + if (rad == 0.0) {
  66 + if (dist > roi) arclength = 0.0; // Circle centre outside ROI
  67 + else arclength = twopi; // Circle centre inside ROI
  68 + }
  69 +
  70 + // ... otherwise we have to handle the general case
  71 + else {
  72 + double dist = roi - dist;
  73 + if (-rad >= dist)
  74 + arclength = 0.0;
  75 + else if (rad <= dist)
  76 + arclength = twopi;
  77 + else {
  78 + double cosrad = cos(rad);
  79 + double sinrad = sin(rad);
  80 + double cosang = (cosroi - cosdist*cosrad) / (sindist*sinrad);
  81 + arclength = acos(cosang);
  82 + }
  83 + }
  84 +
  85 + } // endelse: Circle and ROI centres were not identical
  86 +
  87 + // Return arclength
  88 + return arclength;
  89 +}
... ...
inst/cta/src/GCTASupport.hpp 0 → 100644
  View file @f3cdb72
  1 +/***************************************************************************
  2 + * GCTASupport.hpp - CTA support functions *
  3 + * ----------------------------------------------------------------------- *
  4 + * copyright (C) 2011 by Jurgen Knodlseder *
  5 + * ----------------------------------------------------------------------- *
  6 + * *
  7 + * This program is free software; you can redistribute it and/or modify *
  8 + * it under the terms of the GNU General Public License as published by *
  9 + * the Free Software Foundation; either version 2 of the License, or *
  10 + * (at your option) any later version. *
  11 + * *
  12 + ***************************************************************************/
  13 +/**
  14 + * @file GCTASupport.hpp
  15 + * @brief Definition of support function used by CTA classes
  16 + * @author J. Knodlseder
  17 + */
  18 +
  19 +#ifndef GCTASUPPORT_HPP
  20 +#define GCTASUPPORT_HPP
  21 +
  22 +/* __ Includes ___________________________________________________________ */
  23 +
  24 +/* __ Namespaces _________________________________________________________ */
  25 +
  26 +/* __ Constants __________________________________________________________ */
  27 +
  28 +/* __ Prototypes _________________________________________________________ */
  29 +double cta_roi_arclength(const double& rad, const double& dist,
  30 + const double& cosdist, const double& sindist,
  31 + const double& roi, const double& cosroi);
  32 +
  33 +#endif /* GCTASUPPORT_HPP */
... ...