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Index Page reccyl_c

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Procedure Abstract Required_Reading Keywords Brief_I/O Detailed_Input | Detailed_Output Parameters Exceptions Files Particulars Examples | Restrictions Literature_References Author_and_Institution Version Index_Entries

#### Procedure

       reccyl_c ( Rectangular to cylindrical coordinates )

       void reccyl_c ( ConstSpiceDouble     rectan[3],
                       SpiceDouble        * r,
                       SpiceDouble        * clon,
                       SpiceDouble        * z         )

#### Abstract

       Convert from rectangular to cylindrical coordinates.

#### Required_Reading

       None.

#### Keywords

       CONVERSION
       COORDINATES

#### Brief_I/O

       VARIABLE  I/O  DESCRIPTION
       --------  ---  -------------------------------------------------
       rectan     I   Rectangular coordinates of a point.
       r          O   Distance of the point from Z axis.
       clon       O   Angle (radians) of the point from XZ plane
       z          O   Height of the point above XY plane.

#### Detailed_Input

       rectan      are the rectangular coordinates of the point of interest.

#### Detailed_Output

       r           is the distance of the point of interest from Z axis.

       clon        is the cylindrical angle (in radians) of the point of
                   interest from XZ plane. The `clon' range is [0, 2pi].

       z           is the height of the point above XY plane.

#### Parameters

       None.

#### Exceptions

       Error free.

#### Files

       None.

#### Particulars

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

#### Examples

       The numerical results shown for these examples may differ across
       platforms. The results depend on the SPICE kernels used as
       input, the compiler and supporting libraries, 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.

          /.
             Program reccyl_ex1
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          int main( )
          {

             /.
             Local variables
             ./
             SpiceDouble          clon;
             SpiceDouble          et;
             SpiceDouble          lt;
             SpiceDouble          pos    [3];
             SpiceDouble          rectan [3];
             SpiceDouble          r;
             SpiceDouble          z;

             /.
             Load SPK and LSK kernels, use a meta kernel for
             convenience.
             ./
             furnsh_c ( "reccyl_ex1.tm" );

             /.
             Look up the geometric state of the Moon as seen from
             the Earth at 2017 Mar 20, relative to the J2000
             reference frame.
             ./
             str2et_c ( "2017 Mar 20", &et );

             spkpos_c ( "Moon", et, "J2000", "NONE", "Earth", pos, &lt );

             /.
             Convert the position vector `pos' to cylindrical
             coordinates.
             ./
             reccyl_c ( pos, &r, &clon, &z );

             /.
             Convert the cylindrical to rectangular coordinates.
             ./

             cylrec_c ( r, clon, z, rectan );

             printf( " \n" );
             printf( "Original rectangular coordinates:\n" );
             printf( " \n" );
             printf( " X          (km):  %19.8f\n", pos[0] );
             printf( " Y          (km):  %19.8f\n", pos[1] );
             printf( " Z          (km):  %19.8f\n", pos[2] );
             printf( " \n" );
             printf( "Cylindrical coordinates:\n" );
             printf( " \n" );
             printf( " Radius     (km):  %19.8f\n", r );
             printf( " Longitude (deg):  %19.8f\n", clon*dpr_c ( ) );
             printf( " Z          (km):  %19.8f\n", z );
             printf( " \n" );
             printf( "Rectangular coordinates from cylrec_c:\n" );
             printf( " \n" );
             printf( " X          (km):  %19.8f\n", rectan[0] );
             printf( " Y          (km):  %19.8f\n", rectan[1] );
             printf( " Z          (km):  %19.8f\n", rectan[2] );
             printf( " \n" );

             return ( 0 );
          }

          When this program was executed on a Mac/Intel/cc/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 cylrec_c:

           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.

          /.
             Program reccyl_ex2
          ./
          #include <stdio.h>
          #include "SpiceUsr.h"

          int main( )
          {

             /.
             Local parameters.
             ./
             #define NREC         11

             /.
             Local variables.
             ./
             SpiceDouble          clon;
             SpiceDouble          r;
             SpiceDouble          z;

             SpiceInt             i;

             /.
             Define the input rectangular coordinates.
             ./
             SpiceDouble          rectan [NREC][3] = {
                                       { 0.0,         0.0,         0.0},
                                       { 1.0,         0.0,         0.0},
                                       { 0.0,         1.0,         0.0},
                                       { 0.0,         0.0,         1.0},
                                       {-1.0,         0.0,         0.0},
                                       { 0.0,        -1.0,         0.0},
                                       { 0.0,         0.0,        -1.0},
                                       { 1.0,         1.0,         0.0},
                                       { 1.0,         0.0,         1.0},
                                       { 0.0,         1.0,         1.0},
                                       { 1.0,         1.0,         1.0} };

             /.
             Print the banner.
             ./
             printf( " rect[0]  rect[1]  rect[2]     r       clon      z\n"    );
             printf( " -------  -------  -------  -------  -------  -------\n" );

             /.
             Do the conversion. Output angles in degrees.
             ./
             for ( i = 0; i < NREC; i++ )
             {

                reccyl_c ( rectan[i], &r, &clon, &z );

                printf( "%8.3f %8.3f %8.3f ", rectan[i][0], rectan[i][1],
                                              rectan[i][2]               );
                printf( "%8.3f %8.3f %8.3f\n", r, clon * dpr_c ( ), z );

             }

             return ( 0 );
          }

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

           rect[0]  rect[1]  rect[2]     r       clon      z
           -------  -------  -------  -------  -------  -------
             0.000    0.000    0.000    0.000    0.000    0.000
             1.000    0.000    0.000    1.000    0.000    0.000
             0.000    1.000    0.000    1.000   90.000    0.000
             0.000    0.000    1.000    0.000    0.000    1.000
            -1.000    0.000    0.000    1.000  180.000    0.000
             0.000   -1.000    0.000    1.000  270.000    0.000
             0.000    0.000   -1.000    0.000    0.000   -1.000
             1.000    1.000    0.000    1.414   45.000    0.000
             1.000    0.000    1.000    1.000    0.000    1.000
             0.000    1.000    1.000    1.000   90.000    1.000
             1.000    1.000    1.000    1.414   45.000    1.000

#### Restrictions

       None.

#### Literature_References

       None.

#### Author_and_Institution

       N.J. Bachman        (JPL)
       J. Diaz del Rio     (ODC Space)
       B.V. Semenov        (JPL)
       W.L. Taber          (JPL)
       E.D. Wright         (JPL)

#### Version

       -CSPICE Version 1.3.0, 04-JUL-2021 (JDR)

           Changed the output argument name "lon" to "clon" for consistency
           with other routines.

           Edited the header to comply with NAIF standard.
           Added complete code examples.

       -CSPICE Version 1.2.1, 26-JUL-2016 (BVS)

           Minor headers edits.

       -CSPICE Version 1.2.0, 28-AUG-2001 (NJB)

           Removed tab characters from source file. Include interface
           macro definition header SpiceZim.h.

       -CSPICE Version 1.1.0, 21-OCT-1998 (NJB)

           Made input vector const.

       -CSPICE Version 1.0.0, 08-FEB-1998 (EDW) (WLT)

#### Index_Entries

       rectangular to cylindrical coordinates

#### Link to routine reccyl_c source file reccyl_c.c

    Fri Dec 31 18:41:11 2021