Using the polar coordinate system

In Chapter 2, we talked about polar coordinates. Polar coordinates are just perfect for representing circular or radial symmetric data. Have a quick look back at that chapter, especially at Figure 2.5.

To use polar coordinates, we need to load the corresponding library:

\usepgfplotslibrary{polar}

Then, we have a new polaraxis environment. We can use this just like a normal axis, except that the labels, ticks, and grids are now radial. Take a look at this:

\begin{polaraxis}
  \addplot[domain=0:180, samples=100, thick] {sin(3*x)};
\end{polaraxis}

While a polar plot of sin(x) would give us a simple circle, this relatively simple plot command provides us with the following plot with three leaves:

Figure 13.10 – A trigonometric function in a polar coordinate system

We can drive it on and use a large domain, especially with a fractional argument of the sine function, like this:

\addplot[domain...