\documentclass[crop=true,border=5pt]{standalone}
\usepackage[T1]{fontenc}
\usepackage{libertine}
\usepackage[libertine]{newtxmath}
\input macroperso.tex
\begin{document}
\def\mandeltest#1#2{%
	\def\zx{0}\def\zy{0}%
	\def\zxx{0}\def\zyy{0}%
	\def\mandelresult{1}%
	\for\ii=1to\maxiter\do1{%
		\advance\count255 by1
		\edef\zy{\dimtodec\dimexpr\decmul{\decmul2\zx}\zy pt+#2pt\relax}%
		\edef\zx{\dimtodec\dimexpr\zxx pt-\zyy pt+#1pt\relax}%
		\edef\zxx{\decmul\zx\zx}%
		\edef\zyy{\decmul\zy\zy}%
		\ifdim\dimexpr\zxx pt+\zyy pt\relax>4pt
			\def\mandelresult{0}%
 			\exitfor\ii
		\fi
	}%
}
\def\mandel#1#2{%
	\graphzone{-2}[1]{1}[2]{-1}[1]{1}[2]{%
		\def\maxiter{#2}%
		\edef\plotstuff{\the\dimexpr\xunit/#1\relax}%
		\edef\plotstuff{\vrule height\plotstuff width\plotstuff}%
		\edef\increment{\decdiv{1}{#1}}%
		\count255=0
		\FOR\xxx = -2 to 1 \do \increment{%
			\FOR\yyy = 0 to 1 \do \increment{%
				\mandeltest\xxx\yyy
				\ifnum\mandelresult=1
					\plot(\xxx,\yyy)\plot(\xxx,-\yyy)%
				\fi
			}%
		}%
	\edef\plotstuff{$\scriptstyle\number\count255 $}%
	\plot(-1.99,0.92)%
	}%
}
\xunit=3cm \yunit=3cm \mandel{400}{500}
\end{document}