我写了一个小脚本，用高斯脉冲画一条线。我定义了一些命令（\verticalSpace，\HorizontalSpace等等）来参数化图形。特别是，我定义了\length设置我必须留下的某个空间。\length没有任何限制，或者至少我找不到它们，但我设置了
\newcommand{\length}{1.0}
它可以工作，但如果我设置
\newcommand{\length}{1}
有人能理解为什么吗？
以下是代码
\documentclass{article}
\usepackage{tikz}
\usetikzlibrary{intersections,arrows,positioning}
\begin{document}
\newcommand{\verticalSpace}{1}
\newcommand{\HorizontalSpace}{5}
\newcommand{\length}{1} % HERE! with 1 it does not work, but it does with 1.0
\newcommand{\Ox}{.5}
\newcommand{\Oy}{0}
\newcommand{\pulse}{plot[domain=-\length/2:\length/2,samples=100] function{exp(-20*x*x)/2}}
\begin{figure}
\centering
\begin{tikzpicture}[scale=1]
\tikzstyle{linea}=[line width=1pt]
\tikzstyle{riempimento}=[fillstyle=gradient,gradangle=0,gradbegin=white,gradend=white,gradmidpoint=1.0]
%
\path (\Ox-1*\length,\Oy+0.3) node {$x$};
\filldraw[shift={(\Ox+.5+3*\length+\length/2,\Oy)},linea,draw=blue,top color=blue,shading=axis,shading angle=0] plot[domain=-\length/2:\length/2,samples=100] function{exp(-20*x*x)/2};%\pulse;
\draw[->,linea] (\Ox , \Oy) -- (\Ox+\HorizontalSpace,\Oy);
\end{tikzpicture}
\end{figure}
\end{document}
这是我在序言中添加 \listfiles 后得到的日志文件的内容。
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***********
)
Here is how much of TeX's memory you used:
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56i,5n,55p,463b,601s stack positions out of 5000i,500n,10000p,200000b,50000s
Output written on dummy.dvi (1 page, 4352 bytes).
答案1
引用http://www.manpagez.com/info/gnuplot/gnuplot-4.4.0/gnuplot_21.php, “...gnuplot 同时使用“实数”和“整数”算术... 两种形式之间最重要的区别在于除法：整数除法会截断：5/2 = 2...”
因此，问题在于
domain=-\length/2:\length/2
当 \length 等于 1 时，变为
domain=-0:0
因此没有绘制任何内容，而 \length 等于 1.0 则成为预期
domain=-0.5:0.5