Table of contents
CSPICE_CYLSPH converts cylindrical coordinates to spherical
coordinates.
Given:
r the scalar double precision value for distance of the point from
Z-axis.
help, r
DOUBLE = Scalar
clon the scalar double precision value for the cylindrical angle of
the point from XZ plane as measured in radians.
help, clon
DOUBLE = Scalar
z the scalar double precision value for the height of the point
above XY plane.
help, z
DOUBLE = Scalar
the call:
cspice_cylsph, r, clon, z, radius, colat, slon
returns:
radius the scalar double precision distance of the point from origin.
help, radius
DOUBLE = Scalar
colat the scalar double precision polar angle (co-latitude) of the
point measured in radians.
help, colat
DOUBLE = Scalar
slon the scalar double precision azimuthal angle (longitude) of the
point measured in radians.
help, slon
DOUBLE = Scalar
None.
Any numerical results shown for these examples may differ between
platforms as the results depend on the SPICE kernels used as input
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 spherical
and rectangular coordinates.
Use the meta-kernel shown below to load the required SPICE
kernels.
KPL/MK
File name: cylsph_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.
PRO cylsph_ex1
;;
;; Load SPK and LSK kernels, use a meta kernel for
;; convenience.
;;
cspice_furnsh, 'cylsph_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.
;;
cspice_str2et, '2017 Mar 20', et
cspice_spkpos, 'Moon', et, 'J2000', 'NONE', 'Earth', pos, ltime
;;
;; Convert the position vector `pos' to cylindrical
;; coordinates.
;;
cspice_reccyl, pos, r, clon, z
;;
;; Convert the cylindrical coordinates to spherical.
;;
cspice_cylsph, r, clon, z, radius, colat, slon
;;
;; Convert the spherical coordinates to rectangular.
;;
cspice_sphrec, radius, colat, slon, rectan
print, ' '
print, 'Original rectangular coordinates:'
print, ' '
print, format='(A,F20.8)', ' X (km): ', pos[0]
print, format='(A,F20.8)', ' Y (km): ', pos[1]
print, format='(A,F20.8)', ' Z (km): ', pos[2]
print, ' '
print, 'Cylindrical coordinates:'
print, ' '
print, format='(A,F20.8)', ' Radius (km): ', r
print, format='(A,F20.8)', ' Longitude (deg): ', $
clon*cspice_dpr( )
print, format='(A,F20.8)', ' Z (km): ', z
print, ' '
print, 'Spherical coordinates:'
print, ' '
print, format='(A,F20.8)', ' Radius (km): ', radius
print, format='(A,F20.8)', ' Colatitude (deg): ', $
colat*cspice_dpr( )
print, format='(A,F20.8)', ' Longitude (deg): ', $
slon*cspice_dpr( )
print, ' '
print, 'Rectangular coordinates from cspice_sphrec:'
print, ' '
print, format='(A,F20.8)', ' X (km): ', rectan[0]
print, format='(A,F20.8)', ' Y (km): ', rectan[1]
print, format='(A,F20.8)', ' Z (km): ', rectan[2]
print, ' '
;;
;; It's always good form to unload kernels after use,
;; particularly in IDL due to data persistence.
;;
cspice_kclear
END
When this program was executed on a Mac/Intel/IDL8.x/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
Spherical coordinates:
Radius (km): 403626.33912495
Colatitude (deg): 108.26566077
Longitude (deg): 261.65040211
Rectangular coordinates from cspice_sphrec:
X (km): -55658.44323296
Y (km): -379226.32931475
Z (km): -126505.93063865
2) Create a table showing a variety of cylindrical coordinates
and the corresponding spherical coordinates.
Corresponding spherical and cylindrical coordinates are
listed to three decimal places. All input and output angles
are in degrees.
Example code begins here.
PRO cylsph_ex2
;;
;; Define six sets of cylindrical coordinates, `clon'
;; expressed in degrees.
;;
r = [ 1.d, 1.d, 1.d, 1.d, 0.d, 0.d ]
clon = [ 0.d, 90.d, 180.d, 180.d, 180.d, 33.d ]
z = [ 0.d, 0.d, 1.d, -1.d, 1.d, 0.d ]
;;
;; Print a header for the data output.
;;
print, ' r clon z ', $
' radius slon colat '
print, ' ------- ------- -------', $
' ------- ------- -------'
;;
;; Loop over each set of coordinates...
;;
for i=0, 5 do begin
;;
;; ...convert the `clon' values from degrees to radians
;;
cspice_convrt, clon[i], 'DEGREES', 'RADIANS', lonc_rads
;;
;; ..convert the cylindrical coordinates to spherical
;; coordinates
;;
cspice_cylsph, r[i], lonc_rads, z[i], radius, colat, slon
;;
;; ...convert the `slon' and `colat' values from radians
;; to degrees
;;
cspice_convrt, slon, 'RADIANS', 'DEGREES', slon_degs
cspice_convrt, colat, 'RADIANS', 'DEGREES', colat_degs
;;
;; Print the input and corresponding output.
;;
print, FORMAT='(6D9.3)', r[i], clon[i], z[i], $
radius, slon_degs, colat_degs
endfor
END
When this program was executed on a Mac/Intel/IDL8.x/64-bit
platform, the output was:
r clon z radius slon colat
------- ------- ------- ------- ------- -------
1.000 0.000 0.000 1.000 0.000 90.000
1.000 90.000 0.000 1.000 90.000 90.000
1.000 180.000 1.000 1.414 180.000 45.000
1.000 180.000 -1.000 1.414 180.000 135.000
0.000 180.000 1.000 1.000 180.000 0.000
0.000 33.000 0.000 0.000 33.000 0.000
This returns the spherical coordinates of a point whose position
is input through cylindrical coordinates.
1) If any of the input arguments, `r', `clon' or `z', is
undefined, an error is signaled by the IDL error handling
system.
2) If any of the input arguments, `r', `clon' or `z', is not of
the expected type, or it does not have the expected dimensions
and size, an error is signaled by the Icy interface.
3) If any of the output arguments, `radius', `colat' or `slon',
is not a named variable, an error is signaled by the Icy
interface.
None.
None.
ICY.REQ
None.
J. Diaz del Rio (ODC Space)
E.D. Wright (JPL)
-Icy Version 1.0.1, 10-AUG-2021 (JDR)
Edited the -Examples section to comply with NAIF standard.
Added complete code examples.
Changed the argument names "lonc" and "lon" to "clon" and "slon"
for consistency with other routines.
Added -Parameters, -Exceptions, -Files, -Restrictions,
-Literature_References and -Author_and_Institution sections, and
completed -Particulars section.
Removed reference to the routine's corresponding CSPICE header from
-Abstract section.
Added arguments' type and size information in the -I/O section.
-Icy Version 1.0.0, 16-JUN-2003 (EDW)
cylindrical to spherical
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