% Cardioide: r = 1+cos t
\SUMfunction{\ONEfunction}{\COSfunction}
            {\ffunction}
\POLARfunction{\ffunction}{\cardioide}
\begin{center}
\def\runitdivisions{2}
\setlength{\unitlength}{1.5cm}
\begin{Picture}(-2.5,-2.5)(2.5,2.5)
\polargrid{2}{24}
\pictcolor{blue}\linethickness{1pt}
 \PlotParametricFunction[20]{%
         \cardioide}{0}{\numberTWOPI}
\end{Picture}
$\rho=1+\cos\phi$
\end{center}
