How To LaTeX Constants Constants def \def\a{2.0} \def\b{3.0} \psline(0,0)(\a,\b) newcommand \newcommand{\a}{2.0} \newcommand{\b}{3.0} \psline(0,0)(\a,\b) PostScript \psline(0,0)(!\a\space 2 mul \b\space 2 mul) pgf \pgfmathsetmacro{\myCenterX}{\myWidth / 2} Font