TikZ 中的循环：在数学模式下执行减法

Question

我今天了解到我可以在 TikZ 中执行循环，这让我的生活变得轻松很多......但我想知道如何在数学模式下评估数值表达式。

梅威瑟：

\documentclass[12pt]{article}
\usepackage[margin=2cm]{geometry}
\usepackage{amsmath}
\usepackage [english]{babel}
\usepackage [autostyle, english = american]{csquotes}

%TikZ
\usepackage{tikz}
\usetikzlibrary{arrows}
\usepackage{pgfplots}
\pgfplotsset{compat=1.10}
%TikZ
\begin{document}
\begin{center}    
\begin{tikzpicture}[>=stealth,ultra thick]
    %arrows    
    \draw[->] (0,0) -- (11,0);
    %curly braces
    \foreach \x/\n in {0/35, 2/36, 4/37, 6/38, 8/39}
    \draw[decorate,decoration={brace,amplitude=3pt,mirror}] 
        (\x,-1.25) coordinate (t_k_unten) -- (\x+2,-1.25) coordinate (t_k_opt_unten);
    %vertical dotted lines    
    \foreach \x/\n in {0/35, 2/36, 4/37, 6/38, 8/39, 10/40}
    \draw [dotted] (\x, -1.25) -- (\x, -0.5); 
    %nodes
    \foreach \x/\n in {0/35, 2/36, 4/37, 6/38, 8/39}
    %%%HERE IS THE LINE OF INTEREST:
    \node at (\x+1,-1.75){$K_{35} = \n-35$};
    \draw (-1,0) node[below] {Age};
    %labels for nodes
    \foreach \x/\n in {0/35, 2/36, 4/37, 6/38, 8/39, 10/40}
    \draw (\x,0) node(\n)[below] {\n} -- (\x,0.5);
  \end{tikzpicture}
\end{center}
\end{document}

我特别感兴趣的代码是

\node at (\x+1,-1.75){$K_{35} = \n-35$};

有什么方法可以\n-35在数学模式下执行减法吗？例如，在数学模式下，输出应为 K_35 = 0、K_35 = 1 等。

编辑：我接受的解决方案在数学模式之外创建了一个变量，并在节点中使用了结果。这对于我的目的来说没问题。

Answer 1

这样的事情会起作用吗？

\documentclass[12pt,tikz,border=5pt]{standalone}
\usepackage{amsmath}

\usetikzlibrary{arrows}
\usepackage{pgfplots}
\pgfplotsset{compat=1.10}

\begin{document}

  \begin{tikzpicture}
    [
      >=stealth,
      ultra thick,
    ]
    \draw[->] (0,0) -- (11,0);
    \foreach \x/\n in {0/35, 2/36, 4/37, 6/38, 8/39}
    {
      \draw[decorate,decoration={brace,amplitude=3pt,mirror}] (\x,-1.25) coordinate (t_k_unten) -- (\x+2,-1.25) coordinate (t_k_opt_unten);
      %%%HERE IS THE LINE OF INTEREST:
      \pgfmathsetmacro{\mysubtractresult}{int(\n-35)}
      \node at (\x+1,-1.75){$K_{35} = \mysubtractresult$};
    }
    \foreach \x/\n in {0/35, 2/36, 4/37, 6/38, 8/39, 10/40}
    {
      \draw [dotted] (\x, -1.25) -- (\x, -0.5);
      \draw (\x,0) node(\n)[below] {\n} -- (\x,0.5);
    }
    \draw (-1,0) node[below] {Age};
  \end{tikzpicture}

\end{document}