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Abstract
I/O
Examples
Particulars
Required Reading
Version
Index_Entries

Abstract


   CSPICE_LATCYL converts from latitudinal coordinates to
   cylindrical coordinates.

I/O


   Given:

      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 call:

      [ r, lonc, z] = cspice_latcyl( radius, lon, lat)

   returns:

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

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

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

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

      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 'radius'.

             'r', 'lonc', and 'z' return with the same vectorization
             measure, N, as the 'radius', 'lon', and 'lat'.

Examples


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

   Example (1):

      %
      % Load an SPK, leapseconds, and PCK kernel set.
      %
      cspice_furnsh( 'standard.tm' )

      %
      % Create a vector of scalar times.
      %
      et = [0:2]*2.*cspice_spd;

      %
      % 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' );

      %
      % Convert the array of position vectors 'pos' to latitudinal
      % coordinates.
      %
      [radius, longitude, latitude] = cspice_reclat(pos);

      %
      % Convert the latitudinal coords to cylindrical.
      %
      [r, lonc, z ] = cspice_latcyl( radius, longitude, latitude);

      %
      % Convert the cylindrical to rectangular.
      %
      [rectan] = cspice_cylrec( r, lonc, z);

      %
      % Calculate the relative error against the original position
      % vectors.
      %
      (rectan-pos) ./ pos

   MATLAB outputs:

      1.0e-14 *

                     0  -0.03701547067225   0.63783453323816
      0.02182376758148   0.01641520435413  -0.01531271963894
      0.01912147275010   0.01213804257114   0.02039513446643

      The relative error between the original array of position vectors
      and those that resulted from the various coordinate conversion
      has magnitude on the order of 10^(-14).  A numerical
      demonstration of equality.

   Example (2):

      %
      % Define six sets of latitudinal coordinates, 'lon' and 'lat'
      % expressed in degrees - converted to radians by use
      % of cspice_rpd.
      %
      rad = [ 1.,  1., sqrt(2.), sqrt(2.),   1.,  0. ];
      lon = [ 0., 90.,     180.,     180., 180., 33. ] * cspice_rpd;
      lat = [ 0.,  0.,      45.,     -45.,  90.,  0. ] * cspice_rpd;

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

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

      %
      % Output banner.
      %
      disp('     r         lonc        z        radius      lon        lat   ')
      disp('  --------   --------   --------   --------   --------   --------')

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

      txt = sprintf( '%10.4f %10.4f %10.4f %10.4f %10.4f %10.4f\n', output );
      disp( txt )

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

   MATLAB outputs:

        r         lonc        z        radius      lon        lat
     --------   --------   --------   --------   --------   --------
       1.0000     0.0000     0.0000     1.0000     0.0000     0.0000
       1.0000    90.0000     0.0000     1.0000    90.0000     0.0000
       1.0000   180.0000     1.0000     1.4142   180.0000    45.0000
       1.0000   180.0000    -1.0000     1.4142   180.0000   -45.0000
       0.0000   180.0000     1.0000     1.0000   180.0000    90.0000
       0.0000    33.0000     0.0000     0.0000    33.0000     0.0000

Particulars


   None.

Required Reading


   For important details concerning this module's function, please refer to
   the CSPICE routine latcyl_c.

   MICE.REQ

Version


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

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

   -Mice Version 1.0.0, 09-DEC-2005, EDW (JPL)

Index_Entries


   latitudinal to cylindrical coordinates


Wed Apr  5 18:00:33 2017