\dimexpr \numexpr & calc 包

Question

为什么这不起作用？我使用 Windows、TeX Live 2012 和 pdfLaTeX

\documentclass{article}

\usepackage{calc}

\newlength{\perclenght}

\setlength{\perclenght}{%
                      \dimexpr%
                      ((((336pt*675pt)*(100-7.5))/100)/\textwidth)-\textheight%
                      \relax%
                      }%

\begin{document}
\the\perclenght
\end{document}

Answer 1

感谢 PERCUSSE

这就是答案，对吗？

    \RequirePackage{pgf}%
\newlength\perclength\pgfmathsetlength{\perclength}{%
                                                   ((((3.36*6.75)*(1-(7.5/100)))/(\textwidth/100))-(\textheight/100))*100%
                                                   }%