Procedure

   void recsph_c ( ConstSpiceDouble     rectan[3], 
                   SpiceDouble        * r, 
                   SpiceDouble        * colat,
                   SpiceDouble        * lon      ) 

Abstract

 
   Convert from rectangular coordinates to spherical 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 the origin. 
   colat      O   Angle of the point from the Z-axis in radians
   lon        O   Longitude of the point in radians. 
 

Detailed_Input

 
   rectan     The rectangular coordinates of a point. 
 

Detailed_Output

 
   r          Distance of the point from the origin. 
 
   colat      Angle between the point and the positive z-axis in
              radians. The range of `colat' is [0, pi]. 
 
   lon        Longitude of the point in radians. This is the angle
              between the positive X-axis and the orthogonal
              projection of the point onto the XY plane. `lon'
              increases in the counterclockwise sense about the
              positive Z-axis. The range of `lon' is [-pi, pi].
 

Parameters

 
   None. 
 

Exceptions

 
   Error free. 
 

Files

 
   None. 
 

Particulars

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

Examples

 
   Below are two tables. 
 
   Listed in the first table (under X(1), X(2) and X(3) ) are a 
   number of points whose rectangular coordinates are 
   taken from the set {-1, 0, 1}. 
 
   The result of the code fragment 
 
        recsph_c ( X, r, colat, lon  ) 
 
        Use the CSPICE routine convrt_c to convert the angular 
        quantities to degrees 
 
        convrt_c ( colat, "RADIANS", "DEGREES", colat ) 
        convrt_c (  lon,  "RADIANS", "DEGREES", lon   ) 
 
   are listed to 4 decimal places in the second parallel table under 
   r (radius), colat (co-latitude), and  lon  (longitude). 
 
     X(1)       X(2)     X(3)        r         colat       lon  
     --------------------------      ---------------------------- 
     0.0000     0.0000   0.0000      0.0000     0.0000     0.0000 
     1.0000     0.0000   0.0000      1.0000    90.0000     0.0000 
     0.0000     1.0000   0.0000      1.0000    90.0000    90.0000 
     0.0000     0.0000   1.0000      1.0000     0.0000     0.0000 
    -1.0000     0.0000   0.0000      1.0000    90.0000   180.0000 
     0.0000    -1.0000   0.0000      1.0000    90.0000   -90.0000 
     0.0000     0.0000  -1.0000      1.0000   180.0000     0.0000 
     1.0000     1.0000   0.0000      1.4142    90.0000    45.0000 
     1.0000     0.0000   1.0000      1.4142    45.0000     0.0000 
     0.0000     1.0000   1.0000      1.4142    45.0000    90.0000 
     1.0000     1.0000   1.0000      1.7320    54.7356    45.0000 
 

Restrictions

 
   None. 
 

Literature_References

 
   None. 
 

Author_and_Institution

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

Version

 
   -CSPICE Version 1.1.2, 26-JUL-2016 (BVS)

      Minor headers edits.

   -CSPICE Version 1.1.1, 07-JAN-2002 (NJB) (EDW)

      Fixed description of lon in Brief_I/O and Detailed_I/O
      header sections.

   -CSPICE Version 1.1.0, 22-OCT-1998 (NJB)

      Made input coordinate array const.

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

Index_Entries

 
   rectangular to spherical coordinates 
 

Link to routine recsph_c source file recsph_c.c