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[GREG2\]ELLIPSE Major [Minor [Position_Angle]] [/BOX X Y] [/USER X Y
[code]] [/ARC Theta_min Theta_max] [/FILL [Colour]] [/HATCH [Ipen] [An-
gle] [Separ] [Phase]]
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). This command is useful for plotting beam sizes, uncertainty el-
lipses, pie charts, etc.
Major, Minor are in User Coordinates. X and Y are in User Coordinates
(option /USER) or in Physical Units (centimeters from the bottom left
box corner, option /BOX). Major, Minor, X and Y, can be 1-D arrays of
any size, provided the sizes are the same.
The Position_Angle is ALWAYS in DEGREES, TRIGONOMETRIC ORIENTATION,
starting 0 from X>0 half-axis. Trigonometric means it increases from X>0
half-axis to Y>0 half-axis. As such, orientation can go clockwise or
counter-clockwise depending if the axes are reverted or not, like e.g.
for astronomical plots (X increase to the left). The Position_Angle 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.
/FILL [Colour] will fill the ellipse(s), with the current pen colour or
with the specified colour (see HELP PEN /COL for possibilities). If /ARC
is also present, the filled area is the corresponding pie part, not the
/HATCH will fill the ellipse(s) with parallel lines. The pen (default
current), line orientation in degrees (default 45), the separation in
physical units (default 0.25 cm) and phase between 0 and 1 (default 0)
can be customized. In this case the contour(s) are not drawn. If /ARC is
also present, the filled area is the corresponding pie part, not the