11.3 arc

arc [ item <id> ] [at] <vector> radius <length>
    from <angle> to <angle> [ with { <option> } ]

Arcs (curves with constant radius of curvature, that is, segments of circles) may be drawn on multiplot canvases using the arc command. The at modifier specifies the coordinates of the center of curvature, from which all points on the arc are at the distance given following the radius modifier. The angles start and finish, measured clockwise from the vertical, control where the arc begins and ends. For example, the command

arc at 0,0 radius 2 from 90 to 270

would draw a semi-circle beneath the line $x=0$, centered on the origin with radius $2\, \mathrm{cm}$. The usual style modifiers for lines may be passed after the keyword with; if the fillcolor modifier is specified then the arc will be filled to form a pie-chart slice.

All vector graphics objects placed on multiplot canvases receive unique identification numbers which count sequentially from one, and which may be listed using the list command. By reference to these numbers, they can be deleted and subsequently restored with the delete and undelete commands respectively.