plot.spad line 509 [edit on github]
PlotFunctions1 provides facilities for plotting curves where functions SF -> SF are specified by giving an expression
plot(f, g, t, seg) plots the graph of x = f(t), y = g(t) as t ranges over an interval.
plot(fcn, x, seg) plots the graph of y = f(x) on a interval
plotPolar(f, theta) plots the graph of r = f(theta) as theta ranges from 0 to 2 pi
plotPolar(f, theta, seg) plots the graph of r = f(theta) as theta ranges over an interval