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cspice_reccyl

Table of contents
Abstract
I/O
Parameters
Examples
Particulars
Exceptions
Files
Restrictions
Required_Reading
Literature_References
Author_and_Institution
Version
Index_Entries

Abstract


   CSPICE_RECCYL converts rectangular (Cartesian) coordinates to
   cylindrical coordinates.

I/O


   Given:

      rectan   the array(s) containing the rectangular coordinates of the
               position or set of positions.

               [3,n] = size(rectan); double = class(rectan)

   the call:

       [r, clon, z] = cspice_reccyl( rectan)

   returns:

      r        the value(s) describing the distance of the point of
               interest from z axis.

               [1,n] = size(r); double = class(r)

      clon     the value(s) describing the cylindrical angle of the point of
               interest from the XZ plane measured in radians.

               [1,n] = size(clon); double = class(clon)

      z        the value(s) describing the height of the point above
               the XY plane.

               [1,n] = size(z); double = class(z)

               The arguments `r' and `z' return in the same units associated
               with `rectan'.

               `r', `clon', and `z' return with the same vectorization
               measure as `rectan'.

Parameters


   None.

Examples


   Any numerical results shown for these examples may differ between
   platforms as the results depend on the SPICE kernels used as input
   and the machine specific arithmetic implementation.

   1) Compute the cylindrical coordinates of the position of the Moon
      as seen from the Earth, and convert them to rectangular
      coordinates.

      Use the meta-kernel shown below to load the required SPICE
      kernels.


         KPL/MK

         File name: reccyl_ex1.tm

         This meta-kernel is intended to support operation of SPICE
         example programs. The kernels shown here should not be
         assumed to contain adequate or correct versions of data
         required by SPICE-based user applications.

         In order for an application to use this meta-kernel, the
         kernels referenced here must be present in the user's
         current working directory.

         The names and contents of the kernels referenced
         by this meta-kernel are as follows:

            File name                     Contents
            ---------                     --------
            de421.bsp                     Planetary ephemeris
            naif0012.tls                  Leapseconds


         \begindata

            KERNELS_TO_LOAD = ( 'de421.bsp',
                                'naif0012.tls'  )

         \begintext

         End of meta-kernel


      Example code begins here.


      function reccyl_ex1()

         %
         % Load an SPK and leapseconds kernels.
         %
         cspice_furnsh( 'reccyl_ex1.tm' )

         %
         % Convert the time to ET.
         %
         et = cspice_str2et( '2017 Mar 20' );

         %
         % Retrieve the position of the moon seen from earth at `et'
         % in the J2000 frame without aberration correction.
         %
         [pos, et] = cspice_spkpos( 'MOON', et, 'J2000', 'NONE', 'EARTH' );

         fprintf( 'Original rectangular coordinates:\n' )
         fprintf( '   X          (km): %20.8f\n', pos(1) )
         fprintf( '   Y          (km): %20.8f\n', pos(2) )
         fprintf( '   Z          (km): %20.8f\n', pos(3) )

         %
         % Convert the position vector `pos' to cylindrical
         % coordinates.
         %
         [r, lon, z]           = cspice_reccyl(pos);
         fprintf( '\n' )
         fprintf( 'Cylindrical coordinates:\n' )
         fprintf( '   Radius     (km): %20.8f\n', r )
         fprintf( '   Longitude (deg): %20.8f\n', lon * cspice_dpr )
         fprintf( '   Z          (km): %20.8f\n', z )

         %
         % Convert the cylindrical to rectangular.
         %
         [rectan]              = cspice_cylrec(r, lon, z);
         fprintf( '\n' )
         fprintf( 'Rectangular coordinates from cspice_cylrec:\n' )
         fprintf( '   X          (km): %20.8f\n', rectan(1) )
         fprintf( '   Y          (km): %20.8f\n', rectan(2) )
         fprintf( '   Z          (km): %20.8f\n', rectan(3) )

         %
         % It's always good form to unload kernels after use,
         % particularly in MATLAB due to data persistence.
         %
         cspice_kclear


      When this program was executed on a Mac/Intel/Octave6.x/64-bit
      platform, the output was:


      Original rectangular coordinates:
         X          (km):      -55658.44323296
         Y          (km):     -379226.32931475
         Z          (km):     -126505.93063865

      Cylindrical coordinates:
         Radius     (km):      383289.01777726
         Longitude (deg):         261.65040211
         Z          (km):     -126505.93063865

      Rectangular coordinates from cspice_cylrec:
         X          (km):      -55658.44323296
         Y          (km):     -379226.32931475
         Z          (km):     -126505.93063865


   2) Create a table showing a variety of rectangular coordinates
      and the corresponding cylindrical coordinates.

      Corresponding rectangular and cylindrical coordinates are
      listed to three decimal places. Output angles are in degrees.


      Example code begins here.


      function reccyl_ex2()

         %
         % Define eleven sets of rectangular coordinates.
         %
         rec = [ [ 0., 1., 0., 0., -1., 0., 0., 1., 1., 0., 1. ];         ...
                 [ 0., 0., 1., 0., 0., -1., 0., 1., 0., 1., 1. ];         ...
                 [ 0., 0., 0., 1., 0., 0., -1., 0., 1., 1., 1. ]    ];

         %
         % ...convert the rectangular coordinates to cylindrical coordinates
         %
         [r, clon, z] = cspice_reccyl(rec);

         %
         % Convert `clon' to degrees...
         %
         clon = clon * cspice_dpr;

         %
         % Output banner.
         %
         disp('    r       clon      z     rect(1)  rect(2)  rect(3)')
         disp(' -------  -------  -------  -------  -------  -------')

         %
         % Create an array of values for output.
         %
         output = [ r; clon; z; rec(1,:); rec(2,:); rec(3,:) ];
         txt    = sprintf( '%8.3f %8.3f %8.3f %8.3f %8.3f %8.3f\n', output);
         disp( txt );


      When this program was executed on a Mac/Intel/Octave6.x/64-bit
      platform, the output was:


          r       clon      z     rect(1)  rect(2)  rect(3)
       -------  -------  -------  -------  -------  -------
         0.000    0.000    0.000    0.000    0.000    0.000
         1.000    0.000    0.000    1.000    0.000    0.000
         1.000   90.000    0.000    0.000    1.000    0.000
         0.000    0.000    1.000    0.000    0.000    1.000
         1.000  180.000    0.000   -1.000    0.000    0.000
         1.000  270.000    0.000    0.000   -1.000    0.000
         0.000    0.000   -1.000    0.000    0.000   -1.000
         1.414   45.000    0.000    1.000    1.000    0.000
         1.000    0.000    1.000    1.000    0.000    1.000
         1.000   90.000    1.000    0.000    1.000    1.000
         1.414   45.000    1.000    1.000    1.000    1.000


Particulars


   This routine transforms the coordinates of a point from
   rectangular to cylindrical coordinates.

Exceptions


   1)  If the input argument `rectan' is undefined, an error is
       signaled by the Matlab error handling system.

   2)  If the input argument `rectan' is not of the expected type, or
       it does not have the expected dimensions and size, an error is
       signaled by the Mice interface.

Files


   None.

Restrictions


   None.

Required_Reading


   MICE.REQ

Literature_References


   None.

Author_and_Institution


   J. Diaz del Rio     (ODC Space)
   E.D. Wright         (JPL)

Version


   -Mice Version 1.1.0, 10-AUG-2021 (EDW) (JDR)

       Changed output argument name "lonc" to "clon" for consistency with
       other functions.

       Edited the header to comply with NAIF standard. Added
       meta-kernel to example #1. Updated code example #1 to produce
       formatted output and added a call to cspice_kclear. Added the
       problem statement to both examples.

       Added -Parameters, -Exceptions, -Files, -Restrictions,
       -Literature_References and -Author_and_Institution sections, and
       completed -Particulars section.

       Eliminated use of "lasterror" in rethrow.

       Removed reference to the function's corresponding CSPICE header from
       -Required_Reading section.

   -Mice Version 1.0.1, 01-DEC-2014 (EDW)

       Edited -I/O section to conform to NAIF standard for Mice
       documentation.

   -Mice Version 1.0.0, 22-NOV-2005 (EDW)

Index_Entries


   rectangular to cylindrical coordinates


Fri Dec 31 18:44:26 2021