从宏返回实数

Question

我想要构建返回实数值的宏。例如，我想要类似以下伪代码的内容：

\documentclass{article}

\usepackage{etoolbox}
\usepackage{calculator}

\newcommand{\scale}[3]{%
    \ifnumgreater{#1}{10}
        {\return{#1}}
        {\ifnumgreater{#2}{10}
            {\return{#2}}


                {\return{#3}}
                }
            }

\begin{document}

\begin{tikzpicture}[scale=1]
    %*  Polar Ray - Centerline - Origin at (0,0), 45degs from horizontal to a length of \scale
    \draw [red,dashed] (0,0) -- ++(45:\scale{9}{12}{10});
\end{tikzpicture}

\end{document}

最终，我将使用几种此类宏来评估tikz图表中的几何图形。谢谢

Answer 1

function一种可能的实现是使用TikZ 库声明math：

\documentclass[tikz]{standalone}
\usetikzlibrary{math}
\tikzmath{function myscalefun(\a,\b,\c) {
  if \a>10 then { return \a; } else {
    if \b>10 then { return \b; } else {
      return \c; }; };
};}

\begin{document}
\begin{tikzpicture}[scale=1]
  \clip (0,0) rectangle (15.5,9);
  \foreach \r in {8,...,15} {
    \draw[gray!20] (0,0) circle (\r);
    \node[above] at (\r,0) {\r};
  }
  \draw (0,0) -- ++(45:{myscalefun(9,12,10)});
  \draw (0,0) -- ++(30:{myscalefun(11,12,10)});
  \draw (0,0) -- ++(15:{myscalefun(9,8,9)});
\end{tikzpicture}
\end{document}