Polar Keyword
Used With Routines:  OPLOT,  PLOT
Corresponding System Variable: None.
Polar plots are produced when this keyword is present and nonzero.
The X and Y vector parameters, both of which must be present, are first converted from polar to cartesian coordinates. The first parameter is the radius, and the second is θ, expressed in radians.
To make a polar plot:
PLOT, /Polar, R, Theta