Index Page sphrec_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

       void sphrec_c ( SpiceDouble    r,
                       SpiceDouble    colat,
                       SpiceDouble    lon,
                       SpiceDouble    rectan[3] )

#### Abstract

       Convert from spherical coordinates to rectangular coordinates.

#### Required_Reading

       None.

#### Keywords

        CONVERSION,  COORDINATES

#### Brief_I/O

       VARIABLE  I/O  DESCRIPTION
       --------  ---  --------------------------------------------------
       r          I   Distance of a point from the origin.
       colat      I   Angle of the point from the Z-axis in radians.
       lon        I   Angle of the point from the XZ plane in radians.
       rectan     O   Rectangular coordinates of the point.

#### Detailed_Input

       r          Distance of the point from the origin.

       colat      Angle between the point and the positive z-axis in
                  radians.

       lon        Angle of the projection of the point to the XY plane from
                  the positive X-axis in radians. The positive Y-axis is
                  at longitude PI/2 radians.

#### Detailed_Output

       rectan     The rectangular coordinates of a point.

#### Parameters

       None.

#### Exceptions

       Error free.

#### Files

       None.

#### Particulars

       This routine returns the rectangular coordinates of a point
       whose position is input in spherical coordinates.

       Spherical coordinates are defined by a distance from a central
       reference point, an angle from a reference meridian, and an angle
       from the z-axis.  The co-latitude of the positive Z-axis is
       zero.  The longitude of the posive Y-axis is PI/2 radians.

#### Examples

       Below are two tables.

       Listed in the first table (under r, colat and lon  ) are
       spherical coordinate triples that approximately represent points
       whose rectangular coordinates are taken from the set {-1, 0, 1}.
       (Angular quantities are given in degrees.)

       The result of the code fragment

            Use the CSPICE routine convrt_c to convert the angular
            quantities to radians

            convrt_c ( colat, "DEGREES", "RADIANS", lat  )
            convrt_c (  lon,  "DEGREES", "RADIANS", lon  )

            sphrec_c ( r, colat,  lon, X )

       are listed in the second parallel table under X(1), X(2) and X(3).

         r          colat      lon            X(1)       X(2)     X(3)
         ----------------------------         --------------------------
         0.0000     0.0000     0.0000         0.0000     0.0000   0.0000
         1.0000    90.0000     0.0000         1.0000     0.0000   0.0000
         1.0000    90.0000    90.0000         0.0000     1.0000   0.0000
         1.0000     0.0000     0.0000         0.0000     0.0000   1.0000
         1.0000    90.0000   180.0000        -1.0000     0.0000   0.0000
         1.0000    90.0000   -90.0000         0.0000    -1.0000   0.0000
         1.0000   180.0000     0.0000         0.0000     0.0000  -1.0000
         1.4142    90.0000    45.0000         1.0000     1.0000   0.0000
         1.4142    45.0000     0.0000         1.0000     0.0000   1.0000
         1.4142    45.0000    90.0000         0.0000     1.0000   1.0000
         1.7320    54.7356    45.0000         1.0000     1.0000   1.0000

#### Restrictions

       None.

#### Literature_References

       None.

#### Author_and_Institution

       W.L. Taber      (JPL)
       E.D. Wright     (JPL)

#### Version

       -CSPICE Version 1.0.1, 26-JUL-2016 (BVS)

          Minor headers edits.

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

#### Index_Entries

       spherical to rectangular coordinates

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

    Wed Apr  5 17:54:43 2017