Two-Dimensional Graphics. Statistics Graphics and Curves in Explicit, Parametric and Polar Coordinates - MATLAB Graphical Programming - page 40

Figure 2-12.
2.7 Graphics Functions in Polar Coordinates
MATLAB enables the specific polar command, representing functions in polar coordinates. Its syntax is as follows:
Polar (a, r) represents the curve in polar coordinates r = r (a), using theta in radians .
Polar (a, r, S) represents the curve in polar coordinates r = r (a) with the style of line given
by S , whose values were already specified in the command plot.
eXerCISe 2-9
represent the graph of the curve whose equation in polar coordinates is as follows: r = Sine (2a) Cos (2a) for a
between 0 and 2 p .
the following syntax leads us to the graph in Figure 2-13 :
>> a = 0:0.01:2 * pi;
>> r = sin(2*a) .* cos(2*a);
>> polar(a, r)
Figure 2-13.