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}