Plotting with polar coordinates

All the plots in this chapter up to now have implicitly used rectangular coordinates, usually denoted as x and y. For certain types of information, however, polar geometry is the natural coordinate system. In polar coordinates we have a radius, r, measured from the origin, usually at the center of the graph, and an angle, θ, usually measured counter-clockwise from the horizontal. On the gnuplot command line, the angular coordinate is called t by default. The following is an example of a spiral illustration:

Using polar coordinates we can plot spirals and closed curves that are impossible to define explicitly using rectangular coordinates.

set xtics axis nomirror
set ytics axis nomirror
set zeroaxis
unset border
set samples 500
set polar
plot [0:12*pi] t