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Abstract
I/O
Examples
Particulars
Required Reading
Version
Index_Entries

Abstract


   CSPICE_LATREC converts latitudinal coordinates to rectangular
   (Cartesian) 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:

      rectan = cspice_latrec( radius, lon, lat)

   returns:

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

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

               'rectan' returns with the same units associated with 'radius'.

               'rectan' returns with the vectorization measure, N, as
               '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 to rectangular.
      %
      [rectan] = cspice_latrec(radius, longitude, latitude);

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

   MATLAB outputs:

      1.0e-14 *

     -0.01996090072080  -0.05552320600838   0.63783453323816
      0.02182376758148                  0  -0.01531271963894
      0.01912147275010   0.01213804257114   0.02039513446643

   Example (2):

      %
      % Define eleven sets of latitudinal coordinates.
      %
      r         = [ 0., 1., 1., 1., 1., 1., 1., ...
                                     sqrt(2), sqrt(2), sqrt(2), sqrt(3) ];
      longitude = [ 0., 0., 90., 0. 180., -90., ...
                                     0., 45., 0., 90., 45. ];
      latitude  = [ 0., 0., 0., 90., 0., 0.,    ...
                                     -90., 0., 45., 45., 35.2643 ];

      %
      % ...convert the latitudinal coordinates to rectangular coordinates
      %
      longitude = longitude * cspice_rpd;
      latitude  = latitude  * cspice_rpd;

      rectan = cspice_latrec(r, longitude, latitude);

      %
      % Loop over each set of coordinates for output, convert 'longitude'
      % and 'latitude' to degrees...
      %
      longitude = longitude * cspice_dpr;
      latitude  = latitude  * cspice_dpr;

      %
      % Create an array of values for output.
      %
      output = [ r; longitude; latitude; rectan ];

      %
      % Output banner.
      %
      disp('     r       longitude  latitude       x         y           z   ')
      disp('  --------   --------   --------   --------   --------   --------')

      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       longitude  latitude       x         y           z
     --------   --------   --------   --------   --------   --------
       0.0000     0.0000     0.0000     0.0000     0.0000     0.0000
       1.0000     0.0000     0.0000     1.0000     0.0000     0.0000
       1.0000    90.0000     0.0000     0.0000     1.0000     0.0000
       1.0000     0.0000    90.0000     0.0000     0.0000     1.0000
       1.0000   180.0000     0.0000    -1.0000     0.0000     0.0000
       1.0000   -90.0000     0.0000     0.0000    -1.0000     0.0000
       1.0000     0.0000   -90.0000     0.0000     0.0000    -1.0000
       1.4142    45.0000     0.0000     1.0000     1.0000     0.0000
       1.4142     0.0000    45.0000     1.0000     0.0000     1.0000
       1.4142    90.0000    45.0000     0.0000     1.0000     1.0000
       1.7321    45.0000    35.2643     1.0000     1.0000     1.0000

Particulars


   None.

Required Reading


   For important details concerning this module's function, please refer to
   the CSPICE routine latrec_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, 22-NOV-2005, EDW (JPL)

Index_Entries


   latitudinal to rectangular coordinates


Wed Apr  5 18:00:33 2017