Up: GREG2 Language Internal Help
[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-
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. Option /HATCH will fill them with parallel lines (pen,
angle, separation and phase can be customized, defaults are current, 45
degrees, 0.25 cm and 0 respectively); in this case the contour(s) are
not drawn. 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.