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ELLIPSE
[GREG2\]ELLIPSE Major [Minor [Position_Angle]] [/BOX X Y] [/USER X Y
[code]] [/ARC Theta_min Theta_max] [/FILL [Colour]]
This command draws at current pen position (or at position (X,Y) if op-
tion /BOX or /USER is present) an ellipse of given semi-major axis, se-
mi-minor axis, (default Minor = Major) and Position_Angle (default 0 de-
grees).
Major, Minor, X and Y are in User Coordinates, but Position_Angle is AL-
WAYS in DEGREES, TRIGONOMETRIC ORIENTATION. Major, Minor, X and Y, can
be 1-D arrays of any size, provided the sizes are the same. Position_An-
gle can be indifferently an array, a number, or omitted.
The code suboption in the /USER option, if present, can be any of 'SEC-
ONDS', 'MINUTES', 'DEGREES', 'RADIANS' (in which case the X and Y coor-
dinates are taken to be in the corresponding unit) or 'ABSOLUTE' (in
which case X and Y are taken as absolute coordinates, usually exprimed
in sexagesimal format). The presence of the code suboption is valid only
if a PROJECTION and a SYSTEM (EQUATORIAL or GALACTIC) are both defined.
A portion of the ellipse can be drawn by specifying the boundary angles
in option /ARC (in degrees, trigonometric sense from the position an-
gle). Not compatible with the array mode.
Option /FILL [Colour] will fill the ellipse(s), with the current or
specified colour. If the /ARC option is also present, the filled area is
the corresponding pie part, not the subtended arc.
This command is useful for plotting beam sizes, uncertainty ellipses,
pie charts, etc.
Gildas manager
2011-09-07