绘制指数曲线：尺寸太大

Question

我需要绘制一些这样的曲线：

这些是常数参数 $r$ 在不同值下绘制的曲线。这些曲线的方程是

独立变量是T。这些曲线是针对从上向下增加的 $r$ 值绘制的。xi介于0和 之间1，T介于 0 和 之间。对于任何接近 的\infty曲线的渐近线是T\infty

这是我的尝试，会产生“尺寸太大”错误

\documentclass[12pt]{article}

    \usepackage{tikz}
    \usepackage{pgfplots}
    
    \begin{document}
    \begin{tikzpicture}
    \pgfmathsetmacro{\Ead}{5000};
    \pgfmathsetmacro{\Eai}{10000};
    \pgfmathsetmacro{\R}{8.31};
    \pgfmathsetmacro{\Ad}{30000000};
    \pgfmathsetmacro{\Ai}{70000000};
      \begin{axis}[
    width=10cm, height=6cm,
    xmin=100, xmax=1000,
    ymin=0, ymax=1,
    xtick=\empty, ytick=\empty,
    axis lines=middle,
    x label style={at={(xticklabel cs:1)}, below},
    y label style={at={(yticklabel cs:1)}, above},
    xlabel={$T$}, ylabel={$\xi$},
    ]              
     \addplot [blue, very thick, samples=100, smooth, ]
     { \Ad*(exp(-\Ead/(\R*x))-0.2) / ( \Ad*(exp(-\Ead/(\R*x))) + \Ai*(exp(-\Eai/(\R*x))) ) };
    \end{axis}
        \draw[-stealth] (8,4) -- ++(0,-2) node[midway,above,anchor=west] {$r$ crescente};
    \end{tikzpicture}
    \end{document}

Answer 1

您需要domain像这样设置情节

\documentclass[tikz, border=1cm]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=1.18}    
\begin{document}
\begin{tikzpicture}
\pgfmathsetmacro{\Ead}{5000}
\pgfmathsetmacro{\Eai}{10000}
\pgfmathsetmacro{\R}{8.31}
\pgfmathsetmacro{\Ad}{30000000}
\pgfmathsetmacro{\Ai}{70000000}
\begin{axis}[
width=10cm, height=6cm,
xmin=100, xmax=1000,
ymin=0, ymax=1,
xtick=\empty, ytick=\empty,
axis lines=middle,
x label style={at={(xticklabel cs:1)}, below},
y label style={at={(yticklabel cs:1)}, above},
xlabel={$T$}, ylabel={$\xi$},
]              
\addplot[blue, very thick, domain=100:1000, samples=100, smooth] { \Ad*(exp(-\Ead/(\R*x))-0.2) / ( \Ad*(exp(-\Ead/(\R*x))) + \Ai*(exp(-\Eai/(\R*x))) ) };
\end{axis}
\draw[-stealth] (8,4) -- ++(0,-2) node[midway,above,anchor=west] {$r$ crescente};
\end{tikzpicture}
\end{document}