Add ARC WCS projection (#2541)

Jürgen Knödlseder
1 parent e9d77e48
Showing 18 changed files with 909 additions and 16 deletions
ChangeLog
NEWS
doc/source/admin/release_history/1.6.rst
include/GWcs.hpp
include/GWcsARC.hpp
include/GammaLib.hpp
include/Makefile.am
pyext/GWcsARC.i
pyext/gammalib/sky.i
src/sky/GWcs.cpp
src/sky/GWcsAIT.cpp
src/sky/GWcsARC.cpp
src/sky/GWcsCAR.cpp
src/sky/GWcsMER.cpp
src/sky/GWcsMOL.cpp
src/sky/GWcsSFL.cpp
src/sky/Makefile.am
test/test_GSky.py
-2018-07-03
+2018-07-30
         * Version 1.6.0 released
         ========================
+        Add ARC WCS projection (#2541)
         Add GLog::buffer() method.
         Renamed GPhoton::mcid() to GPhoton::mc_id()
         Remove at() methods from Python interface (#2515)
 New Features and Important Changes in GammaLib 1.6.0
-5 July 2018
+30 July 2018
 1. Introduction
@@ -13,6 +13,7 @@ made since the last release of GammaLib.
 ---------------------------------
 The following classes have been added:
 - GModelSpectralExponential
+- GWcsARC
 The following classes have been removed:
 - none
@@ -205,6 +206,10 @@ None
 12. Sky module
 --------------
+The class GWcsARC was added to handle ARC WCS projections (#2541). In addition
+the private GWcs::prj_bchk() method was added to implement boundary checking
+similar to the checking done in WCS.
+
 A precomputation cache was added to the GWcs::dir2pix() and GWcs::pix2dir()
 methods so that results are not recomputed for the same arguments. This should
 provide some speed-up as it avoids unnecessary coordinate transformations.
@@ -34,6 +34,8 @@ Bug fixes
 Improvements
 ------------
+* [`2541 <https://cta-redmine.irap.omp.eu/issues/2541>`_] -
+  Add ``ARC`` WCS projection.
 * Add ``GLog::buffer()`` method
 * Renamed ``GPhoton::mcid()`` to ``GPhoton::mc_id()``
 * [`2513 <https://cta-redmine.irap.omp.eu/issues/2513>`_] -
@@ -146,6 +146,13 @@ protected:
     // Methods adapted from wcslib::prj.c
     void         prj_ini(void) const;
     void         prj_off(const double& phi0, const double& theta0) const;
+    int          prj_bchk(const double& tol,
+                          const int&    nphi,
+                          const int&    ntheta,
+                          const int&    spt,
+                          double*       phi,
+                          double*       theta,
+                          int*          stat) const;
     virtual void prj_set(void) const = 0;
     virtual void prj_x2s(int nx, int ny, int sxy, int spt, 
                          const double* x, const double* y,
+/***************************************************************************
+ *   GWcsARC.hpp - Zenithal/azimuthal equidistant (ARC) projection class   *
+ * ----------------------------------------------------------------------- *
+ *  copyright (C) 2018 by Juergen Knoedlseder                              *
+ * ----------------------------------------------------------------------- *
+ *                                                                         *
+ *  This program 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.                                    *
+ *                                                                         *
+ *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  *
+ *                                                                         *
+ ***************************************************************************/
+/**
+ * @file GWcsARC.hpp
+ * @brief Zenithal/azimuthal equidistant (ARC) projection class definition
+ * @author Juergen Knoedlseder
+ */
+
+#ifndef GWCSARC_HPP
+#define GWCSARC_HPP
+
+/* __ Includes ___________________________________________________________ */
+#include <string>
+#include "GWcs.hpp"
+
+
+/***********************************************************************//**
+ * @class GWcsARC
+ *
+ * @brief Zenithal/azimuthal equidistant (ARC) projection class definition
+ *
+ * This class implements the Zenithal/azimuthal equidistant projection for
+ * the World Coordinate System.
+ ***************************************************************************/
+class GWcsARC : public GWcs {
+
+public:
+    // Constructors and destructors
+    GWcsARC(void);
+    GWcsARC(const std::string& coords,
+            const double& crval1, const double& crval2,
+            const double& crpix1, const double& crpix2,
+            const double& cdelt1, const double& cdelt2);
+    GWcsARC(const GWcsARC& wcs);
+    virtual ~GWcsARC(void);
+
+    // Operators
+    GWcsARC& operator=(const GWcsARC& wcs);
+
+    // Implemented pure virtual base class methods
+    virtual void        clear(void);
+    virtual GWcsARC*    clone(void) const;
+    virtual std::string classname(void) const;
+    virtual std::string code(void) const;
+    virtual std::string name(void) const;
+    virtual std::string print(const GChatter& chatter = NORMAL) const;
+
+private:
+    // Private methods
+    void init_members(void);
+    void copy_members(const GWcsARC& wcs);
+    void free_members(void);
+    void prj_set(void) const;
+    void prj_x2s(int nx, int ny, int sxy, int spt, 
+                 const double* x, const double* y,
+                 double* phi, double* theta, int* stat) const;
+    void prj_s2x(int nphi, int ntheta, int spt, int sxy,
+                 const double* phi, const double* theta,
+                 double* x, double* y, int* stat) const;
+};
+
+
+/***********************************************************************//**
+ * @brief Return class name
+ *
+ * @return String containing the class name ("GWcsARC").
+ ***************************************************************************/
+inline
+std::string GWcsARC::classname(void) const
+{
+    return ("GWcsARC");
+}
+
+
+/***********************************************************************//**
+ * @brief Return projection code
+ *
+ * @return Projection code.
+ *
+ * Returns the projection code "ARC".
+ ***************************************************************************/
+inline
+std::string GWcsARC::code(void) const
+{
+    return "ARC";
+}
+
+
+/***********************************************************************//**
+ * @brief Return projection name
+ *
+ * @return Projection name.
+ *
+ * Returns the projection name.
+ ***************************************************************************/
+inline
+std::string GWcsARC::name(void) const
+{
+    return "Zenithal/azimuthal equidistant";
+}
+
+#endif /* GWCSARC_HPP */
 /***************************************************************************
  *          GammaLib.hpp - Gamma-Ray Astronomy Library Header file         *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2006-2017 by Juergen Knoedlseder                         *
+ *  copyright (C) 2006-2018 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -155,6 +155,7 @@
 #include "GWcsRegistry.hpp"
 #include "GWcs.hpp"
 #include "GWcsAIT.hpp"
+#include "GWcsARC.hpp"
 #include "GWcsAZP.hpp"
 #include "GWcsCAR.hpp"
 #include "GWcsGLS.hpp"
 #############################################################################
 # Makefile.am for include module                                            #
 # ------------------------------------------------------------------------- #
-# Copyright (C) 2016-2017 Juergen Knoedlseder                               #
+# Copyright (C) 2016-2018 Juergen Knoedlseder                               #
 # ------------------------------------------------------------------------- #
 #                                                                           #
 #  This program is free software: you can redistribute it and/or modify     #
@@ -117,6 +117,7 @@ pkginclude_HEADERS = GammaLib.hpp \
                      GWcsRegistry.hpp \
                      GWcs.hpp \
                      GWcsAIT.hpp \
+                     GWcsARC.hpp \
                      GWcsAZP.hpp \
                      GWcsCAR.hpp \
                      GWcsGLS.hpp \
+/***************************************************************************
+ *    GWcsARC.i - Zenithal/azimuthal equidistant (ARC) projection class    *
+ * ----------------------------------------------------------------------- *
+ *  copyright (C) 2018 by Juergen Knoedlseder                              *
+ * ----------------------------------------------------------------------- *
+ *                                                                         *
+ *  This program 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.                                    *
+ *                                                                         *
+ *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  *
+ *                                                                         *
+ ***************************************************************************/
+/**
+ * @file GWcsARC.i
+ * @brief Zenithal/azimuthal equidistant (ARC) projection class definition
+ * @author Juergen Knoedlseder
+ */
+%{
+/* Put headers and other declarations here that are needed for compilation */
+#include "GWcsARC.hpp"
+%}
+
+
+/***********************************************************************//**
+ * @class GWcsARC
+ *
+ * @brief Zenithal/azimuthal equidistant (ARC) projection class
+ ***************************************************************************/
+class GWcsARC : public GWcs {
+public:
+    // Constructors and destructors
+    GWcsARC(void);
+    GWcsARC(const std::string& coords,
+            const double& crval1, const double& crval2,
+            const double& crpix1, const double& crpix2,
+            const double& cdelt1, const double& cdelt2);
+    GWcsARC(const GWcsARC& wcs);
+    virtual ~GWcsARC(void);
+
+    // Implemented pure virtual methods
+    virtual void        clear(void);
+    virtual GWcsARC*    clone(void) const;
+    virtual std::string classname(void) const;
+    virtual std::string code(void) const;
+    virtual std::string name(void) const;
+};
+
+
+/***********************************************************************//**
+ * @brief GWcsARC class extension
+ ***************************************************************************/
+%extend GWcsARC {
+    GWcsARC copy() {
+        return (*self);
+    }
+};
 /***************************************************************************
  *                          sky.i - Sky module                             *
  * ----------------------------------------------------------------------- *
- *  copyright (C) 2011-2017 by Jurgen Knodlseder                           *
+ *  copyright (C) 2011-2018 by Jurgen Knodlseder                           *
  * ----------------------------------------------------------------------- *
  *                                                                         *
  *  This program is free software: you can redistribute it and/or modify   *
@@ -122,6 +122,7 @@ namespace std {
 %include "GWcsRegistry.i"
 %include "GWcs.i"
 %include "GWcsAIT.i"
+%include "GWcsARC.i"
 %include "GWcsAZP.i"
 %include "GWcsCAR.i"
 %include "GWcsGLS.i"
@@ -3090,3 +3090,109 @@ void GWcs::prj_off(const double&amp; phi0, const double&amp; theta0) const
     // Return
     return;
 }
+
+
+/***********************************************************************//**
+ * @brief Performs bounds checking on native spherical coordinates
+ *
+ * @param[in] tol Tolerance for the bounds check [deg]
+ * @param[in] nphi Number of bins in phi.
+ * @param[in] ntheta Number of bins in theta.
+ * @param[in] spt Step size.
+ * @param[in,out] phi Pointer to phi array [deg]
+ * @param[in,out] theta Pointer to theta array [deg]
+ * @param[in,out] stat Pointer to status array.
+ *
+ * Performs bounds checking on native spherical coordinates. As returned by
+ * the deprojection (x2s) routines, native longitude is expected to lie in
+ * the closed interval [-180,180], with latitude in [-90,90].
+ *
+ * A tolerance may be specified to provide a small allowance for numerical
+ * imprecision. Values that lie outside the allowed range by not more than
+ * the specified tolerance will be adjusted back into range.
+ *
+ * Code adapted from prj.c::prjbchk().
+ ***************************************************************************/
+int GWcs::prj_bchk(const double& tol,
+                   const int&    nphi,
+                   const int&    ntheta,
+                   const int&    spt,
+                   double*       phi,
+                   double*       theta,
+                   int*          stat) const
+{
+    // Initialize result
+    int status = 0;
+
+    // Continue only if bounds checking is requested
+    if (m_bounds) {
+
+        // Initialise array pointers
+        register double* phip   = phi;
+        register double* thetap = theta;
+        register int*    statp  = stat;
+
+        // Loop over all theta bins
+        for (int itheta = 0; itheta < ntheta; ++itheta) {
+
+            // Loop over all phi bins
+            for (int iphi = 0; iphi < nphi; ++iphi, phip += spt, thetap += spt, statp++) {
+
+                // Skip values already marked as illegal
+                if (*statp == 0) {
+
+                    // Check lower phi boundary
+                    if (*phip < -180.0) {
+                        if (*phip < -180.0-tol) {
+                            *statp = 1;
+                            status = 1;
+                        }
+                        else {
+                            *phip = -180.0;
+                        }
+                    }
+
+                    // Check upper phi boundary
+                    else if (180.0 < *phip) {
+                        if (180.0+tol < *phip) {
+                            *statp = 1;
+                            status = 1;
+                        }
+                        else {
+                            *phip = 180.0;
+                        }
+                    }
+
+                    // Check lower theta boundary
+                    if (*thetap < -90.0) {
+                        if (*thetap < -90.0-tol) {
+                            *statp = 1;
+                            status = 1;
+                        }
+                        else {
+                            *thetap = -90.0;
+                        }
+                    }
+
+                    // Check upper theta boundary
+                    else if (90.0 < *thetap) {
+                        if (90.0+tol < *thetap) {
+                            *statp = 1;
+                            status = 1;
+                        }
+                        else {
+                            *thetap = 90.0;
+                        }
+                    }
+
+                } // endif: values were marked as valid
+
+            } // endfor: looped over phi
+
+        } // endfor: looped over theta
+
+    } // endif: bounds checking was requested
+
+    // Return status
+    return status;
+}
 /***************************************************************************
- *               GWcsAIT.cpp - Aitoff (AIT) projection class               *
+ *   GWcsAIT.cpp - Zenithal/azimuthal equidistant (AIT) projection class               *
  * ----------------------------------------------------------------------- *
  *  copyright (C) 2013-2018 by Juergen Knoedlseder                         *
  * ----------------------------------------------------------------------- *
@@ -306,21 +306,21 @@ void GWcsAIT::prj_set(void) const
     // Initialise projection parameters
     m_w.assign(4, 0.0);
-    
+
     // Set undefined parameters
     if (m_r0 == 0.0) {
         m_r0 = gammalib::rad2deg;
     }
-    
+
     // Precompute 
     m_w[0] = 2.0 * m_r0 * m_r0;
     m_w[1] = 1.0 / (2.0 * m_w[0]);
     m_w[2] = m_w[1] / 4.0;
     m_w[3] = 1.0 / (2.0 * m_r0);
-    
+
     // Compute fiducial offset
     prj_off(0.0, 0.0);
-    
+
     // Return
     return;
 }
@@ -381,7 +381,7 @@ void GWcsAIT::prj_x2s(int nx, int ny, int sxy, int spt,
     // Initialise status code and statistics
     int status    = 0;
     int n_invalid = 0;
-    
+
     // Do x dependence
     const double* xp     = x;
     int           rowoff = 0;
@@ -480,6 +480,11 @@ void GWcsAIT::prj_x2s(int nx, int ny, int sxy, int spt,
         throw GException::wcs_invalid_x_y(G_PRJ_X2S, n_invalid);
     }
+    // Do bounds checking on the native coordinates
+  	// if (prj->bounds&4 && prjbchk(1.0e-13, nx, my, spt, phi, theta, stat)) {
+    //   if (!status) status = PRJERR_BAD_PIX_SET("aitx2s");
+  	// }
+
     // Return
     return;
 }
@@ -537,7 +542,7 @@ void GWcsAIT::prj_s2x(int nphi, int ntheta, int spt, int sxy,
     // Initialise status code and statistics
     int status    = 0;
     int n_invalid = 0;
-    
+
     // Do phi dependence
     const double* phip   = phi;
     int           rowoff = 0;
@@ -563,7 +568,7 @@ void GWcsAIT::prj_s2x(int nphi, int ntheta, int spt, int sxy,
     double*       yp     = y;
     int*          statp  = stat;
     for (int itheta = 0; itheta < ntheta; ++itheta, thetap += spt) {
-    
+
         // Compute sin(theta) and cos(theta)
         double sinthe;
         double costhe;
@@ -578,12 +583,12 @@ void GWcsAIT::prj_s2x(int nphi, int ntheta, int spt, int sxy,
         } // endfor: phi
     } // endfor: theta
-  
+
     // Handle status code
     if (status == 4) {
         throw GException::wcs_invalid_phi_theta(G_PRJ_S2X, n_invalid);
     }
-    
+
     // Return
     return;
 }
+/***************************************************************************
+ *   GWcsARC.cpp - Zenithal/azimuthal equidistant (ARC) projection class   *
+ * ----------------------------------------------------------------------- *
+ *  copyright (C) 2018 by Juergen Knoedlseder                              *
+ * ----------------------------------------------------------------------- *
+ *                                                                         *
+ *  This program 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.                                    *
+ *                                                                         *
+ *  This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.  *
+ *                                                                         *
+ ***************************************************************************/
+/**
+ * @file GWcsARC.cpp
+ * @brief Zenithal/azimuthal equidistant (ARC) projection class implementation
+ * @author Juergen Knoedlseder
+ */
+
+/* __ Includes ___________________________________________________________ */
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include "GException.hpp"
+#include "GMath.hpp"
+#include "GTools.hpp"
+#include "GWcsARC.hpp"
+#include "GWcsRegistry.hpp"
+
+/* __ Method name definitions ____________________________________________ */
+#define G_PRJ_X2S    "GWcsARC::prj_x2s(int, int, int, int, double*, double*,"\
+                                                   " double*, double*, int*)"
+#define G_PRJ_S2X    "GWcsARC::prj_s2x(int, int, int, int, double*, double*,"\
+                                                   " double*, double*, int*)"
+
+/* __ Macros _____________________________________________________________ */
+
+/* __ Coding definitions _________________________________________________ */
+
+/* __ Debug definitions __________________________________________________ */
+
+/* __ Local prototypes ___________________________________________________ */
+
+/* __ Constants __________________________________________________________ */
+
+/* __ Globals ____________________________________________________________ */
+const GWcsARC      g_wcs_arc_seed;
+const GWcsRegistry g_wcs_arc_registry(&g_wcs_arc_seed);
+
+
+/*==========================================================================
+ =                                                                         =
+ =                         Constructors/destructors                        =
+ =                                                                         =
+ ==========================================================================*/
+
+/***********************************************************************//**
+ * @brief Void constructor
+ ***************************************************************************/
+GWcsARC::GWcsARC(void) : GWcs()
+{
+    // Initialise class members
+    init_members();
+
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
+ * @brief Constructor
+ *
+ * @param[in] coords Coordinate system.
+ * @param[in] crval1 X value of reference pixel.
+ * @param[in] crval2 Y value of reference pixel.
+ * @param[in] crpix1 X index of reference pixel (starting from 1).
+ * @param[in] crpix2 Y index of reference pixel (starting from 1).
+ * @param[in] cdelt1 Increment in x direction at reference pixel [deg].
+ * @param[in] cdelt2 Increment in y direction at reference pixel [deg].
+ ***************************************************************************/
+GWcsARC::GWcsARC(const std::string& coords,
+                 const double& crval1, const double& crval2,
+                 const double& crpix1, const double& crpix2,
+                 const double& cdelt1, const double& cdelt2) :
+                 GWcs(coords, crval1, crval2, crpix1, crpix2, cdelt1, cdelt2)
+
+{
+    // Initialise class members
+    init_members();
+
+    // Setup WCS derived parameters
+    wcs_set();
+
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
+ * @brief Copy constructor
+ *
+ * @param[in] wcs World Coordinate System.
+ ***************************************************************************/
+GWcsARC::GWcsARC(const GWcsARC& wcs) : GWcs(wcs)
+{
+    // Initialise class members for clean destruction
+    init_members();
+
+    // Copy members
+    copy_members(wcs);
+
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
+ * @brief Destructor
+ ***************************************************************************/
+GWcsARC::~GWcsARC(void)
+{
+    // Free members
+    free_members();
+
+    // Return
+    return;
+}
+
+
+/*==========================================================================
+ =                                                                         =
+ =                               Operators                                 =
+ =                                                                         =
+ ==========================================================================*/
+
+/***********************************************************************//**
+ * @brief Assignment operator
+ *
+ * @param[in] wcs World Coordinate System.
+ * @return World Coordinate System.
+ ***************************************************************************/
+GWcsARC& GWcsARC::operator=(const GWcsARC& wcs)
+{
+    // Execute only if object is not identical
+    if (this != &wcs) {
+
+        // Copy base class members
+        this->GWcs::operator=(wcs);
+
+        // Free members
+        free_members();
+
+        // Initialise private members for clean destruction
+        init_members();
+
+        // Copy members
+        copy_members(wcs);
+
+    } // endif: object was not identical
+
+    // Return this object
+    return *this;
+}
+
+
+/*==========================================================================
+ =                                                                         =
+ =                             Public methods                              =
+ =                                                                         =
+ ==========================================================================*/
+
+/***********************************************************************//**
+ * @brief Clear instance
+ *
+ * This method properly resets the object to an initial state.
+ ***************************************************************************/
+void GWcsARC::clear(void)
+{
+    // Free class members (base and derived classes, derived class first)
+    free_members();
+    this->GWcs::free_members();
+    this->GSkyProjection::free_members();
+
+    // Initialise members
+    this->GSkyProjection::init_members();
+    this->GWcs::init_members();
+    init_members();
+
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
+ * @brief Clone instance
+ *
+ * @return Pointer to deep copy of Zenithal/azimuthal equidistant projection.
+ ***************************************************************************/
+GWcsARC* GWcsARC::clone(void) const
+{
+    return new GWcsARC(*this);
+}
+
+
+
+/***********************************************************************//**
+ * @brief Print WCS information
+ *
+ * @param[in] chatter Chattiness.
+ * @return String containing WCS information.
+ ***************************************************************************/
+std::string GWcsARC::print(const GChatter& chatter) const
+{
+    // Initialise result string
+    std::string result;
+
+    // Continue only if chatter is not silent
+    if (chatter != SILENT) {
+
+        // Append header
+        result.append("=== GWcsARC ===");
+
+        // Append information
+        result.append(wcs_print(chatter));
+
+    } // endif: chatter was not silent
+
+    // Return result
+    return result;
+}
+
+
+/*==========================================================================
+ =                                                                         =
+ =                             Private methods                             =
+ =                                                                         =
+ ==========================================================================*/
+
+/***********************************************************************//**
+ * @brief Initialise class members
+ ***************************************************************************/
+void GWcsARC::init_members(void)
+{
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
+ * @brief Copy class members
+ *
+ * @param[in] wcs World Coordinate System.
+ ***************************************************************************/
+void GWcsARC::copy_members(const GWcsARC& wcs)
+{
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
+ * @brief Delete class members
+ ***************************************************************************/
+void GWcsARC::free_members(void)
+{
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
+ * @brief Setup of projection
+ *
+ * This method sets up the projection information. The method has been
+ * adapted from the wcslib function prj.c::arcset.
+ *
+ *   Given and/or returned:
+ *      m_r0      Reset to 180/pi if 0.
+ *      m_phi0    Reset to  0.0 if undefined.
+ *      m_theta0  Reset to 90.0 if undefined.
+ *
+ *   Returned:
+ *      m_x0      Fiducial offset in x.
+ *      m_y0      Fiducial offset in y.
+ *      m_w[0]    r0*(pi/180)
+ *      m_w[1]    (180/pi)/r0
+ ***************************************************************************/
+void GWcsARC::prj_set(void) const
+{
+    // Signal that projection has been set (needs to be done before calling
+    // the prj_off() method to avoid an endless loop)
+    m_prjset = true;
+
+    // Initialise projection parameters
+    m_w.assign(2, 0.0);
+    
+    // Set undefined parameters
+    if (m_r0 == 0.0) {
+        m_r0   = gammalib::rad2deg;
+        m_w[0] = 1.0;
+        m_w[1] = 1.0;
+    }
+    else {
+        m_w[0] = m_r0 * gammalib::deg2rad;
+        m_w[1] = 1.0/m_w[0];
+    }
+    
+    // Compute fiducial offset
+    prj_off(0.0, 0.0);
+    
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
+ * @brief Pixel-to-spherical deprojection
+ *
+ * @param[in] nx X vector length.
+ * @param[in] ny Y vector length (0=no replication).
+ * @param[in] sxy Input vector step.
+ * @param[in] spt Output vector step.
+ * @param[in] x Vector of projected x coordinates.
+ * @param[in] y Vector of projected y coordinates.
+ * @param[out] phi Longitude of the projected point in native spherical
+ *                 coordinates [deg].
+ * @param[out] theta Latitude of the projected point in native spherical
+ *                   coordinates [deg].
+ * @param[out] stat Status return value for each vector element (always 0)
+ *
+ * @exception GException::wcs_invalid_x_y
+ *            One or more of the (x,y) coordinates were invalid, as indicated
+ *            by the stat vector.
+ *
+ * Deproject pixel (x,y) coordinates in the plane of projection to native
+ * spherical coordinates (phi,theta).
+ *
+ * This method has been adapted from the wcslib function prj.c::aitx2s().
+ * The interface follows very closely that of wcslib. In contrast to the
+ * wcslib routine, however, the method assumes that the projection has been
+ * setup previously (as this will be done by the constructor).
+ ***************************************************************************/
+void GWcsARC::prj_x2s(int nx, int ny, int sxy, int spt, 
+                      const double* x, const double* y,
+                      double* phi, double* theta, int* stat) const
+{
+    // Initialize projection if required
+    if (!m_prjset) {
+        prj_set();
+    }
+
+    // Set value replication length mx,my
+    int mx;
+    int my;
+    if (ny > 0) {
+        mx = nx;
+        my = ny;
+    } 
+    else {
+        mx = 1;
+        my = 1;
+        ny = nx;
+    }
+
+    // Do x dependence
+    const double* xp     = x;
+    int           rowoff = 0;
+    int           rowlen = nx * spt;
+    for (int ix = 0; ix < nx; ++ix, rowoff += spt, xp += sxy) {
+        double  xj     = *xp + m_x0;
+        double* phip   = phi + rowoff;
+        for (int iy = 0; iy < my; ++iy, phip += rowlen) {
+            *phip   = xj;
+        }
+    }
+
+    // Do y dependence
+    const double* yp     = y;
+    double*       phip   = phi;
+    double*       thetap = theta;
+    int*          statp  = stat;
+    for (int iy = 0; iy < ny; ++iy, yp += sxy) {
+        double yj  = *yp + m_y0;
+        double yj2 = yj * yj;
+        for (int ix = 0; ix < mx; ++ix, phip += spt, thetap += spt) {
+            double xj = *phip;
+            double r  = std::sqrt(xj*xj + yj2);
+            if (r == 0.0) {
+                *phip   =  0.0;
+                *thetap = 90.0;
+            }
+            else {
+                *phip   = gammalib::atan2d(xj, -yj);
+                *thetap = 90.0 - r * m_w[1];
+            }
+            *(statp++) = 0;
+        }
+    }
+
+    // Do boundary checking
+    int status = prj_bchk(1.0e-13, nx, my, spt, phi, theta, stat);
+    
+    // Handle status code
+    if (status != 0) {
+        std::string msg = "One or more of the (x, y) coordinates were invalid "
+                          "for the "+name()+" ("+code()+") projection.";
+        throw GException::invalid_value(G_PRJ_X2S, msg);
+    }
+
+    // Return
+    return;
+}
+
+
+/***********************************************************************//**
+ * @brief Generic spherical-to-pixel projection
+ *
+ * @param[in] nphi Longitude vector length.
+ * @param[in] ntheta Latitude vector length (0=no replication).
+ * @param[in] spt Input vector step.
+ * @param[in] sxy Output vector step.
+ * @param[in] phi Longitude vector of the projected point in native spherical
+ *                coordinates [deg].
+ * @param[in] theta Latitude vector of the projected point in native spherical
+ *                  coordinates [deg].
+ * @param[out] x Vector of projected x coordinates.
+ * @param[out] y Vector of projected y coordinates.
+ * @param[out] stat Status return value for each vector element (always 0)
+ *
+ * @exception GException::wcs_invalid_phi_theta
+ *            One or more of the (phi,theta) coordinates were invalid, as
+ *            indicated by the stat vector.
+ *
+ * Project native spherical coordinates (phi,theta) to pixel (x,y)
+ * coordinates in the plane of projection.
+ *
+ * This method has been adapted from the wcslib function prj.c::aits2x().
+ * The interface follows very closely that of wcslib. In contrast to the
+ * wcslib routine, however, the method assumes that the projection has been
+ * setup previously (as this will be done by the constructor).
+ ***************************************************************************/
+void GWcsARC::prj_s2x(int nphi, int ntheta, int spt, int sxy,
+                      const double* phi, const double* theta,
+                      double* x, double* y, int* stat) const
+{
+    // Initialize projection if required
+    if (!m_prjset) {
+        prj_set();
+    }
+
+    // Set value replication length mphi,mtheta
+    int mphi;
+    int mtheta;
+    if (ntheta > 0) {
+        mphi   = nphi;
+        mtheta = ntheta;
+    } 
+    else {
+        mphi   = 1;
+        mtheta = 1;
+        ntheta = nphi;
+    }
+
+    // Initialise status code and statistics
+    //int status    = 0;
+    //int n_invalid = 0;
+    
+    // Do phi dependence
+    const double* phip   = phi;
+    int           rowoff = 0;
+    int           rowlen = nphi * sxy;
+    for (int iphi = 0; iphi < nphi; ++iphi, rowoff += sxy, phip += spt) {
+        double sinphi;
+        double cosphi;
+        gammalib::sincosd(*phip, &sinphi, &cosphi);
+        double* xp = x + rowoff;
+        double* yp = y + rowoff;
+        for (int itheta = 0; itheta < mtheta; ++itheta) {
+            *xp = sinphi;
+            *yp = cosphi;
+            xp += rowlen;
+            yp += rowlen;
+        }
+    }
+
+    // Do theta dependence
+    const double* thetap = theta;
+    double*       xp     = x;
+    double*       yp     = y;
+    int*          statp  = stat;
+    for (int itheta = 0; itheta < ntheta; ++itheta, thetap += spt) {
+    
+        // Compute r
+        double r = m_w[0] * (90.0 - *thetap);
+
+        // Do phi dependence
+        for (int iphi = 0; iphi < mphi; ++iphi, xp += sxy, yp += sxy) {
+            *xp        =  r * (*xp) - m_x0;
+            *yp        = -r * (*yp) - m_y0;
+            *(statp++) = 0;
+        } // endfor: phi
+
+    } // endfor: theta
+
+    // Handle status code
+    /*
+    if (status == 4) {
+        throw GException::wcs_invalid_phi_theta(G_PRJ_S2X, n_invalid);
+    }
+    */
+    
+    // Return
+    return;
+}
@@ -34,6 +34,8 @@
 #include "GWcsRegistry.hpp"
 /* __ Method name definitions ____________________________________________ */
+#define G_PRJ_X2S    "GWcsCAR::prj_x2s(int, int, int, int, double*, double*,"\
+                                                   " double*, double*, int*)"
 /* __ Macros _____________________________________________________________ */
@@ -383,6 +385,16 @@ void GWcsCAR::prj_x2s(int nx, int ny, int sxy, int spt,
         }
     }
+    // Do boundary checking
+    int status = prj_bchk(1.0e-13, nx, my, spt, phi, theta, stat);
+    
+    // Handle status code
+    if (status != 0) {
+        std::string msg = "One or more of the (x, y) coordinates were invalid "
+                          "for the "+name()+" ("+code()+") projection.";
+        throw GException::invalid_value(G_PRJ_X2S, msg);
+    }
+
     // Return
     return;
 }
@@ -34,6 +34,8 @@
 #include "GWcsRegistry.hpp"
 /* __ Method name definitions ____________________________________________ */
+#define G_PRJ_X2S    "GWcsMER::prj_x2s(int, int, int, int, double*, double*,"\
+                                                   " double*, double*, int*)"
 /* __ Macros _____________________________________________________________ */
@@ -383,6 +385,16 @@ void GWcsMER::prj_x2s(int nx, int ny, int sxy, int spt,
         }
     }
+    // Do boundary checking
+    int status = prj_bchk(1.0e-13, nx, my, spt, phi, theta, stat);
+    
+    // Handle status code
+    if (status != 0) {
+        std::string msg = "One or more of the (x, y) coordinates were invalid "
+                          "for the "+name()+" ("+code()+") projection.";
+        throw GException::invalid_value(G_PRJ_X2S, msg);
+    }
+
     // Return
     return;
 }
@@ -529,6 +529,16 @@ void GWcsMOL::prj_x2s(int nx, int ny, int sxy, int spt,
         throw GException::wcs_invalid_x_y(G_PRJ_X2S, n_invalid);
     }
+    // Do boundary checking
+    status = prj_bchk(1.0e-11, nx, my, spt, phi, theta, stat);
+    
+    // Handle status code
+    if (status != 0) {
+        std::string msg = "One or more of the (x, y) coordinates were invalid "
+                          "for the "+name()+" ("+code()+") projection.";
+        throw GException::invalid_value(G_PRJ_X2S, msg);
+    }
+
     // Return
     return;
 }
@@ -428,6 +428,16 @@ void GWcsSFL::prj_x2s(int nx, int ny, int sxy, int spt,
         throw GException::wcs_invalid_x_y(G_PRJ_X2S, n_invalid);
     }
+    // Do boundary checking
+    status = prj_bchk(1.0e-12, nx, my, spt, phi, theta, stat);
+    
+    // Handle status code
+    if (status != 0) {
+        std::string msg = "One or more of the (x, y) coordinates were invalid "
+                          "for the "+name()+" ("+code()+") projection.";
+        throw GException::invalid_value(G_PRJ_X2S, msg);
+    }
+
     // Return
     return;
 }
 #############################################################################
 # Makefile.am for sky module                                                #
 # ------------------------------------------------------------------------- #
-# Copyright (C) 2016-2017 Juergen Knoedlseder                               #
+# Copyright (C) 2016-2018 Juergen Knoedlseder                               #
 # ------------------------------------------------------------------------- #
 #                                                                           #
 #  This program is free software: you can redistribute it and/or modify     #
@@ -38,6 +38,7 @@ sources = GSkyDir.cpp \
           GWcsRegistry.cpp \
           GWcs.cpp \
           GWcsAIT.cpp \
+          GWcsARC.cpp \
           GWcsAZP.cpp \
           GWcsCAR.cpp \
           GWcsGLS.cpp \
@@ -358,6 +358,17 @@ class Test(gammalib.GPythonTestSuite):
         # Return
         return
+    # Test ARC projection
+    def _test_skymap_arc(self):
+        """
+        Test ARC projection.
+        """
+        # Execute generic test
+        self._test_skymap_proj('ARC')
+
+        # Return
+        return
+
     # Test AZP projection
     def _test_skymap_azp(self):
         """
@@ -565,6 +576,7 @@ class Test(gammalib.GPythonTestSuite):
         test_support._pickeling(self, gammalib.GSkyRegionMap())
         test_support._pickeling(self, gammalib.GSkyRegions())
         test_support._pickeling(self, gammalib.GWcsAIT())
+        test_support._pickeling(self, gammalib.GWcsARC())
         test_support._pickeling(self, gammalib.GWcsAZP())
         test_support._pickeling(self, gammalib.GWcsCAR())
         test_support._pickeling(self, gammalib.GWcsGLS())
@@ -596,6 +608,7 @@ class Test(gammalib.GPythonTestSuite):
         test_support._pickeling(self, gammalib.GSkyRegionMap(map))
         test_support._pickeling(self, gammalib.GSkyRegions(regions))
         test_support._pickeling(self, gammalib.GWcsAIT('GAL',1.0,2.0,1.0,1.0,0.1,0.1))
+        test_support._pickeling(self, gammalib.GWcsARC('GAL',1.0,2.0,1.0,1.0,0.1,0.1))
         test_support._pickeling(self, gammalib.GWcsAZP('GAL',1.0,2.0,1.0,1.0,0.1,0.1))
         test_support._pickeling(self, gammalib.GWcsCAR('GAL',1.0,2.0,1.0,1.0,0.1,0.1))
         test_support._pickeling(self, gammalib.GWcsGLS('GAL',1.0,2.0,1.0,1.0,0.1,0.1))
@@ -622,6 +635,7 @@ class Test(gammalib.GPythonTestSuite):
         self.append(self._test_operators, 'Test sky map operators')
         self.append(self._test_skymap_healpix, 'Test HEALPix map')
         self.append(self._test_skymap_ait, 'Test AIT projection map')
+        self.append(self._test_skymap_arc, 'Test ARC projection map')
         self.append(self._test_skymap_azp, 'Test AZP projection map')
         self.append(self._test_skymap_car, 'Test CAR projection map')
         self.append(self._test_skymap_gls, 'Test GLS projection map')