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