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Abstract
I/O
Examples
Particulars
Required Reading
Version
Index_Entries

Abstract


   CSPICE_LATSPH converts latitudinal coordinates to spherical
   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:

      [rho, colat, lons] = cspice_latsph( radius, lon, lat)

   returns:

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

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

      colat    the value(s) describing the angle between the point and the
               positive z-axis, measured in radians (also referred to
               as the polar angle).

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

      lons     the value(s) describing the angle of the projection of the
               point to the XY plane from the positive X-axis, measured
               in radians, with range:

                   -pi < lons <= pi

               The positive Y-axis is at longitude PI/2 radians.

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

              The argument 'rho' returns in the same units associated
              with 'radius'.

              'rho', 'colat', and 'lons' return with the same 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 coords to spherical.
      %
      [rho, colat, lon] = cspice_latsph( radius, longitude, latitude);

      %
      % Convert the spherical to rectangular.
      %
      [rectan] = cspice_sphrec(radius, colat, lon);

      %
      % 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  -0.04855217028457   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).

    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 spherical coordinates
      %
      [rho, colat, slon] = cspice_latsph(rad, lon, lat);

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

      %
      % Output banner.
      %
      disp('    rho       colat       slon       rad        lon        lat   ')
      disp('  --------   --------   --------   --------   --------   --------')

      %
      % Create an array of values for output.
      %
      output = [ rho; colat; slon; 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:

          rho       colat       slon       rad        lon        lat
        --------   --------   --------   --------   --------   --------
          1.0000    90.0000     0.0000     1.0000     0.0000     0.0000
          1.0000    90.0000    90.0000     1.0000    90.0000     0.0000
          1.4142    45.0000   180.0000     1.4142   180.0000    45.0000
          1.4142   135.0000   180.0000     1.4142   180.0000   -45.0000
          1.0000     0.0000   180.0000     1.0000   180.0000    90.0000
          0.0000    90.0000    33.0000     0.0000    33.0000     0.0000

Particulars


   None.

Required Reading


   For important details concerning this module's function, please refer to
   the CSPICE routine latsph_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 spherical coordinates


Wed Apr  5 18:00:33 2017