I'm trying to draw illustrations of Gaussian ellipsoids using shaded ellipses. In simple terms what I'm after is a way to have a light shade throughout the outer edge of the ellipse and a darker shade towards the centre of the ellipse (i.e the contours of a 2D Gaussian distribution should have the same shade proportional to the density). I've tried radial shading but it's not the effect I'm looking for.
Here is a simple example (which does not produce the shading result I want).
\begin{tikzpicture}
\def\particles{(20,-3),(22,-5),(22,-7),(19,-8) }
\pgfsetfillopacity{0.6};
\foreach \point in \particles{
\shade[rotate around={30:\point},inner color=green] \point ellipse (1 and 2);
\draw[fill=black] \point circle (2mm);
}
\end{tikzpicture}
Can anyone please suggest a method to draw the Gaussian ellipsoids?
\documentclass
and the appropriate packages so that those trying to help don't have to recreate it. This is especially important fortikz
as there are numerous libraries. – Peter Grill May 21 '13 at 6:36