我创建了一个代码来获取一个符号表。我已经尝试了现有的解决方案，但我不喜欢它们。我几乎已经实现了我的所有目标，但我获得的表格如下：
这是我创建的代码的一个工作示例
\documentclass[11pt]{article}
\usepackage{tikz, pgfplots, pgfmath, pgffor, amssymb}
\begin{document}
Sign table for the function
\[
f(x) = \frac{x(x^2-1)}{x+2}
\]
\bigskip
\begin{tikzpicture}[scale=.80]
% variables and sign array
%
\def\h{.9}; % row height
\def\w{2.5}; % column width
%
\def\zeros{{"-2", "-1", 0, 1}}; % zeros and point of not existence
\def\factors{{"x+2", "x", "x^2-1", "f(x)"}};
\def\signs{{{"-" ,"\nexists" ,"+" , ,"+" , ,"+" , ,"+"}, % "\nexists" is for point of not existence
{"-" , ,"-" , ,"-" ,"0" ,"+" , ,"+"},
{"+" , ,"+" ,"0" ,"-" , ,"-" ,"0" ,"+"},
{"+" ,"\nexists" ,"-" ,"0" ,"+" ,"0" ,"-" ,"0" ,"+"},
}};
%
\pgfmathsetmacro\nzeros{dim(\zeros)-1}; % number of zeros
\pgfmathsetmacro\ncol{2*dim(\zeros)}; % Number of columns
\pgfmathsetmacro\nrow{dim(\factors)-1}; % number of rows
% Abscissa axis
%
\draw[->] (-\w, 0) -- ({(\nzeros+1)*\w+0.125}, 0) node[above]{$x$};
\draw (-\w, {-\nrow*\h}) -- ({(\nzeros+1)*\w}, {-\nrow*\h});
% Zeros and vertical (dotted) lines
%
\foreach \i in {0,...,\nzeros} {
\draw[dotted, gray!80] (\i*\w, {-(\nrow+0.125)*\h}) -- (\i*\w, 0);
\draw (\i*\w, 0) -- (\i*\w, +0.125) node[above] {$\pgfmathparse{\zeros[\i]}\pgfmathresult$};
}
% Signs and zeros table
%
\foreach \row in {0,...,\nrow} {
\node[left] at (-\w-0.125, {-(\row+0.5)*\h}) {\footnotesize signs of\, $\pgfmathparse{\factors[\row]}\pgfmathresult$};
\foreach \col in {0,...,\ncol} {
\node at ({(\col-1)*\w/2}, {-(\row+0.5)*\h}) {$\pgfmathparse{\signs[\row][\col]}\pgfmathresult$}; % <-- (1)
}
}
\end{tikzpicture}
\end{document}
现在我想要：
- 转换代码以使其具有功能，即
\signtable{..zeros...}{...factors...}{...signs...}
- 避免零和 \nexists 与虚线重叠。我尝试在 (1) 中使用一个框（参见代码中的注释标记），但它也创建了一个字符为空的框。我尝试在 (1) 中使用轮廓，但它给了我以下错误
Incomplete \iffalse; all text was ignored after line 52.}
第 52 行是最后一个 \foreach 的结尾
此外，还可以通过自动计算最后一行来改进代码。
有人能帮助我吗？