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如何使用 pgfplots 繪製涉及有理指數的函數？

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如何使用 pgfplots 繪製涉及有理指數的函數？

我試圖繪製的冪函數沒有完全顯示出來，我嘗試過更改域和其他內容，但無濟於事，我可以在這裡獲得一些幫助嗎？

\documentclass{article}
\usepackage{amsmath}
\usepackage{pgfplots}
\pgfplotsset{compat=1.13}

\begin{document}
\begin{tikzpicture}
\begin{axis}[
     axis lines = center,
    xlabel = $x$,
    ylabel = {$y$},
    xmax = {4},
    xmin = {-1},
    ymax = {2},
    ymin = {-2},
    legend pos = outer north east
]
\addplot [
    domain=-10:10, 
    samples=100, 
    color=black,
]
{x^(1/2)};
\addlegendentry{$y=\sqrt{x}$}
\addplot [
    domain=-5:5, 
    samples=100, 
    color=blue,
]
{x^(1/4)};
\addlegendentry{$y=x^{\frac{1}{4}}$}
\end{axis}
\end{tikzpicture}
\begin{tikzpicture}
\begin{axis}[
    axis lines = center,
    xlabel = $x$,
    ylabel = {$y$},
    xmax = {4},
    xmin = {-4},
    ymax = {2},
    ymin = {-2},
    legend pos = north west
]
\addplot [
    domain=-10:10, 
    samples=100, 
    color=black,
]
{x^(1/3)};
\addlegendentry{$y=x^{\frac{1}{3}}$}
\addplot [
    domain=-10:10, 
    samples=100, 
    color=blue,
]
{x^(1/5)};
\addlegendentry{$y=x^{\frac{1}{5}}$}
\end{axis}
\end{tikzpicture}
\end{document}

答案1

您可以調整解決方案PGF 數學函數計算立方根產生計算三次根和五次根的函數：

在此輸入影像描述

參考：

代碼：

\documentclass{article}
\usepackage{amsmath}
\usepackage{pgfplots}
\pgfplotsset{compat=1.13}

\pgfmathdeclarefunction{CubeRoot}{1}{%
    \pgfmathparse{ifthenelse(#1<0,-1,1)*exp((ln(abs(#1)))/3)}%
}

\pgfmathdeclarefunction{FifthRoot}{1}{%
    \pgfmathparse{ifthenelse(#1<0,-1,1)*exp((ln(abs(#1)))/5)}%
}


\begin{document}\noindent
\begin{tikzpicture}
\begin{axis}[
     axis lines = center,
    xlabel = $x$,
    ylabel = {$y$},
    xmax = {4},
    xmin = {-1},
    ymax = {2},
    ymin = {-2},
    legend pos = south east
]
\addplot [
    domain=0:4, 
    samples=100, 
    color=orange,
    line width=1.0pt,
]
{(x)^(1/2)};
\addlegendentry{$y=\sqrt{x}$}
\addplot [
    domain=0:5, 
    samples=100, 
    color=blue,
    line width=1.0pt,
]
{(x)^(1/4)};
\addlegendentry{$y=x^{\frac{1}{4}}$}
\end{axis}
\end{tikzpicture}
\par
\noindent
\begin{tikzpicture}
\begin{axis}[
    axis lines = center,
    xlabel = $x$,
    ylabel = {$y$},
    xmax = 4,
    xmin = -4,
    ymax = 2,
    ymin = -2,
    legend pos = south east,
    clip=true,
]
\addplot [
    domain=-4:4, 
    samples=100, 
    color=blue, 
    line width=1.0pt,
]
{CubeRoot(x)};
\addlegendentry{$y=x^{\frac{1}{3}}$}
\addplot [
    domain=-4:4, 
    samples=100, 
    color=red,
    line width=1.0pt,
]
{FifthRoot(x)};
\addlegendentry{$y=x^{\frac{1}{5}}$}
\end{axis}
\end{tikzpicture}
\end{document}

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