2PLOT: plot arc - draw an arc

Usage: plot arc <x> <y> <a> [<b> [<f1> <f2>]]

draws a circle, an ellipse, or part of a circle or ellipse with the
center at (x,y), and half axes a and b. If b is omitted, a circle with
radius a (measured in the x-direction) is drawn. Optionally, only the
part of the ellipse starting and ending with phase angles f1 and f2,
respectively, is drawn. The phase angle is 0 on the positive x-axis
and increases counterclockwise. This command can also be used in list
mode, where the parameters are vector expressions.
