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cspice_cyllat

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

Abstract


   CSPICE_CYLLAT converts cylindrical coordinates to latitudinal
   coordinates.

I/O


   Given:

      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 call:

      [radius, lon, lat] = cspice_cyllat( r, clon, z )

   returns:

      radius   the value(s) describing the distance of the position
               from the origin.

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

      lon      the value(s) describing the angle of the position from
               the XZ plane measured in radians.

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

      lat      the value(s) describing the angle of the position from the
               XY plane measured in radians.

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

               The argument `radius' returns in the same units associated
               with `r' and `z'.

               `radius', `lon', and `lat' return with the same
               vectorization measure (N) as the `r', `clon', and `z'.

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 latitudinal and
      rectangular coordinates.

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


         KPL/MK

         File name: cyllat_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 cyllat_ex1()

         %
         % Load an SPK and leapseconds kernels.
         %
         cspice_furnsh( 'cyllat_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 coords to latitudinal.
         %
         [radius3, lon3, lat3] = cspice_cyllat(r, lon, z);
         fprintf( '\n' )
         fprintf( 'Latitudinal coordinates:\n' )
         fprintf( '   Radius     (km): %20.8f\n', radius3 )
         fprintf( '   Longitude (deg): %20.8f\n', lon3 * cspice_dpr )
         fprintf( '   Latitude  (deg): %20.8f\n', lat3 * cspice_dpr )

         %
         % Convert the latitudinal to rectangular.
         %
         [rectan]              = cspice_latrec(radius3, lon3, lat3);
         fprintf( '\n' )
         fprintf( 'Rectangular coordinates from cspice_latrec:\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

      Latitudinal coordinates:
         Radius     (km):      403626.33912495
         Longitude (deg):         261.65040211
         Latitude  (deg):         -18.26566077

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


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

      Corresponding cylindrical and latitudinal coordinates are
      listed to four decimal places. All input and output angles
      are in degrees.


      Example code begins here.


      function cyllat_ex2()

         %
         % Define six sets of cylindrical coordinates, `clon' expressed
         % in degrees - converted to radians by use of cspice_rpd.
         %
         r     = [ 1.,  1.,   1.,   1.,   0.,  0. ];
         clon  = [ 0., 90., 180., 180., 180., 33. ] * cspice_rpd;
         z     = [ 0.,  0.,   1.,  -1.,   1.,  0. ];

         %
         % ...convert the cylindrical coordinates to latitudinal coordinates
         %
         [rad, lon, lat] = cspice_cyllat(r, clon, z);

         %
         % ...convert angular measure to degrees.
         %
         clon = clon * cspice_dpr;
         lon  = lon  * cspice_dpr;
         lat  = lat  * cspice_dpr;

         %
         % Output banner.
         %
         disp(['     r       clon        z    ',                          ...
               '   radius     lon       lat   '])
         disp(['  -------  --------  -------- ',                          ...
               '  -------  --------  -------- '])

         %
         % Create an array of values for output.
         %
         output = [ r; clon; z; rad; lon; lat ];

         txt = sprintf( '%9.3f %9.3f %9.3f %9.3f %9.3f %9.3f\n',          ...
                        output);
         disp( txt )


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


           r       clon        z       radius     lon       lat
        -------  --------  --------   -------  --------  --------
          1.000     0.000     0.000     1.000     0.000     0.000
          1.000    90.000     0.000     1.000    90.000     0.000
          1.000   180.000     1.000     1.414   180.000    45.000
          1.000   180.000    -1.000     1.414   180.000   -45.000
          0.000   180.000     1.000     1.000   180.000    90.000
          0.000    33.000     0.000     0.000    33.000     0.000


Particulars


   This routine converts coordinates given in cylindrical
   coordinates to coordinates in latitudinal coordinates.

   Latitudinal coordinates are defined by a distance from a central
   reference point, an angle from a reference meridian, and an angle
   above the equator of a sphere centered at the central reference
   point.

Exceptions


   1)  If any of the input arguments, `r', `clon' or `z', is
       undefined, an error is signaled by the Matlab error handling
       system.

   2)  If any of the input arguments, `r', `clon' or `z', is not of
       the expected type, or it does not have the expected dimensions
       and size, an error is signaled by the Mice interface.

   3)  If the input vectorizable arguments `r', `clon' and `z' do not
       have the same measure of vectorization (N), 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 the input argument name "lonc" to "clon" for consistency
       with other routines.

       Edited the -Examples section 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, 30-OCT-2014 (EDW)

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

   -Mice Version 1.0.0, 01-DEC-2005 (EDW)

Index_Entries


   cylindrical to latitudinal


Fri Dec 31 18:44:23 2021