next up previous contents index
Next: EXTREMA Up: GREG2 Language Internal Help Previous: CONVERT   Contents   Index


        [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 are in User Coordinates, but Position_Angle  is  ALWAYS  in
    DEGREES, TRIGONOMETRIC ORIENTATION. X and Y are in User Coordinates (op-
    tion /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. Position_Angle can  be  indiffer-
    ently 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.

Gildas manager 2014-07-01