Table of contents
CSPICE_CYLREC converts cylindrical coordinates to rectangular
(Cartesian) coordinates.
Given:
r a double precision scalar or N-vector describing the distance of
the point of interest from z axis.
help, r
DOUBLE = Scalar or DOUBLE = Array[N]
Output units are the same as the units associated with `r'.
clon a double precision scalar or N-vector describing the cylindrical
angle of the point of interest from XZ plane measured in
radians.
help, clon
DOUBLE = Scalar or DOUBLE = Array[N]
z a double precision scalar or N-vector describing the height of
the point above XY plane.
help, z
DOUBLE = Scalar or DOUBLE = Array[N]
the call:
cspice_cylrec, r, clon, z, rectan
returns:
rectan a double precision 3-vector or 3xN array containing the
rectangular coordinates of the position or set of positions.
help, rectan
DOUBLE = Array[3] or DOUBLE = Array[3,N]
The output units associated with `rectan' are those associated
with the input `z'.
`rectan' returns with the same measure of vectorization (N)
as `r', `clon', and `z'.
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 rectangular
coordinates.
Use the meta-kernel shown below to load the required SPICE
kernels.
KPL/MK
File name: cylrec_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 cylrec_ex1
;;
;; Load SPK and LSK kernels, use a meta kernel for
;; convenience.
;;
cspice_furnsh, 'cylrec_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 to rectangular coordinates.
;;
cspice_cylrec, r, clon, z, 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, 'Rectangular coordinates from cspice_cylrec:'
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, ' '
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
Rectangular coordinates from cspice_cylrec:
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 rectangular coordinates.
Corresponding rectangular and cylindrical coordinates are
listed to three decimal places. Input angles are in degrees.
Example code begins here.
PRO cylrec_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 ', $
' rect[0] rect[1] rect[2]'
print, ' ------- ------- -------', $
' ------- ------- ------- '
;;
;; Convert the longitudes to radians.
;;
lonc_rads = clon * cspice_rpd()
;;
;; ..convert the cylindrical coordinates to rectangular
;; coordinates
;;
cspice_cylrec, r, lonc_rads, z, rectan
;;
;; Load the data for easy output.
;;
output = dblarr( 6, 6 )
output(0,*) = r
output(1,*) = clon
output(2,*) = z
output(3,*) = rectan[0,*]
output(4,*) = rectan[1,*]
output(5,*) = rectan[2,*]
;;
;; Output the coordinate table.
;;
print, FORMAT='(6D9.3)', output
END
When this program was executed on a Mac/Intel/IDL8.x/64-bit
platform, the output was:
r clon z rect[0] rect[1] rect[2]
------- ------- ------- ------- ------- -------
1.000 0.000 0.000 1.000 0.000 0.000
1.000 90.000 0.000 0.000 1.000 0.000
1.000 180.000 1.000 -1.000 0.000 1.000
1.000 180.000 -1.000 -1.000 0.000 -1.000
0.000 180.000 1.000 -0.000 0.000 1.000
0.000 33.000 0.000 0.000 0.000 0.000
This routine transforms the coordinates of a point from
cylindrical to rectangular 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 the input vectorizable arguments `r', `clon' and `z' do not
have the same measure of vectorization (N), an error is
signaled by the Icy interface.
4) If the output argument `rectan' 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 1.2.0, 10-AUG-2021 (JDR)
Edited the -Examples section to comply with NAIF standard.
Added complete code examples.
Changed the input argument name "lonc" to "clon" 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 1.1.1, 05-FEB-2008 (EDW)
Edited -I/O section, replaced comment
"returns with the same order"
with
"returns with the same measure of vectorization"
-Icy Version 1.1.0, 12-SEP-2004 (EDW)
Added capability to process vectors 'r', 'lonc', and 'z'
as input, returning array 'rectan' on output.
-Icy Version 1.0.0, 16-JUN-2003 (EDW)
cylindrical to rectangular
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