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相图更好的编码

tag-icon • tag-icon pgfplots foreach
相图更好的编码

因此我设法得到了如下所示的幅度和相位图：

\documentclass[12pt]{article}
\usepackage{tikz}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{pgfplots}
\usepackage{float}
\begin{document}
    \begin{figure}[H]\centering
        \begin{tikzpicture}
            \begin{axis}[
            width = 5 in,
            height = 1 in,
            scale only axis,
            at={(0in,3.5in)},
            xtick={-pi, -(3/4)*pi,  -(1/2)*pi, -(1/4)*pi,  (1/4)*pi, (1/2)*pi, (3/4)*pi, pi},
            xticklabels={$-\pi$, $-\frac{3\pi}{4}$,  $-\frac{\pi}{2}$, $-\frac{\pi}{4}$,$\frac{\pi}{4}$,  $\frac{\pi}{2}$, $\frac{3\pi}{4}$, $\pi$},
            ytick={1},
            xmin=-pi,xmax=pi,
            ymin=0,ymax=1,
            axis lines=center,
            axis line style=->, xlabel = {$\omega$}, ylabel={$\left|H\left(e^{j\omega}\right)\right|$},
            %every axis y label/.style={at={(0,1)},anchor=south},
            %every axis x label/.style={at={(1,2/3)},anchor=west},
            every axis x label/.style={at={(ticklabel* cs:1.05)}, anchor=west,},
            every axis y label/.style={at={(ticklabel* cs:1.05)}, anchor=south,},
            domain=-pi:pi,samples=101]
                \addplot [blue,thick, domain = -pi:pi] {abs(sin(2*deg(x)))};
            \end{axis}
            
            \begin{axis}[ %Phase plot
            width = 5 in,
            height = 2.5 in,
            scale only axis,
            at={(0in,0in)},
            xtick={-pi, -(3/4)*pi,  -(1/2)*pi, -(1/4)*pi,  (1/4)*pi, (1/2)*pi, (3/4)*pi, pi},
            xticklabels={$-\pi$, $-\frac{3\pi}{4}$,  $-\frac{\pi}{2}$, $-\frac{\pi}{4}$,$\frac{\pi}{4}$,  $\frac{\pi}{2}$, $\frac{3\pi}{4}$, $\pi$},
            ytick={-pi, -(1/2)*pi, (1/2)*pi, pi},
            yticklabels={$-\pi$,  $-\frac{\pi}{2}$,  $\frac{\pi}{2}$,  $\pi$},
            xmin=-pi,xmax=pi,
            ymin=-pi,ymax=pi,
            axis lines=center,
            axis line style=->, xlabel = {$\omega$}, ylabel={$\angle H\left(e^{j\omega}\right)$},
            %every axis y label/.style={at={(0,1)},anchor=south},
            %every axis x label/.style={at={(1,2/3)},anchor=west},
            every axis x label/.style={at={(ticklabel* cs:1.05)}, anchor=west,},
            every axis y label/.style={at={(ticklabel* cs:1.05)}, anchor=south,},
            domain=-pi:pi,samples=101]
                \addplot [blue,thick, domain = -pi: -pi/2] { pi/2 - 2*(x + pi)};
                \addplot [blue, thick] coordinates{(-pi/2, -pi/2) (-pi/2, pi/2)};
                \addplot [blue,thick, domain = -pi/2: 0] { pi/2 - 2*(x + pi/2)};
                \addplot [blue, thick] coordinates{(0, -pi/2) (0, pi/2)};
                \addplot [blue,thick, domain = 0:pi/2] { pi/2 - 2*x};
                \addplot [blue, thick] coordinates{(pi/2, -pi/2) (pi/2, pi/2)};
                \addplot [blue,thick, domain = pi/2:pi] { pi/2 - 2*(x - pi/2)};
            
            \end{axis}
        \end{tikzpicture} 
    \end{figure}
\end{document}

输出：

在此处输入图片描述

我想知道是否有更简洁（甚至更好）的方法来绘制如图所示的相位图。我试过了\pgfplotsinvokeforeach，但一直出错。

答案1

您要求提供情节。以下是情节：

\addplot[blue,thick,samples at={-2,-1,-1,0,0,1,1,2}]
             ({x*pi/2},{int(\coordindex/2)==\coordindex/2?pi/2:-pi/2});

;-)

\documentclass[12pt]{article}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{pgfplots}
\pgfplotsset{compat=1.17}
\usepackage{float}
\begin{document}
    \begin{figure}[H]\centering
        \begin{tikzpicture}
            \begin{axis}[
            width = 5 in,
            height = 1 in,
            scale only axis,
            at={(0in,3.5in)},
            xtick={-pi, -(3/4)*pi,  -(1/2)*pi, -(1/4)*pi,  (1/4)*pi, (1/2)*pi, (3/4)*pi, pi},
            xticklabels={$-\pi$, $-\frac{3\pi}{4}$,  $-\frac{\pi}{2}$, $-\frac{\pi}{4}$,$\frac{\pi}{4}$,  $\frac{\pi}{2}$, $\frac{3\pi}{4}$, $\pi$},
            ytick={1},
            xmin=-pi,xmax=pi,
            ymin=0,ymax=1,
            axis lines=center,
            axis line style=->, xlabel = {$\omega$}, ylabel={$\left|H\left(e^{j\omega}\right)\right|$},
            %every axis y label/.style={at={(0,1)},anchor=south},
            %every axis x label/.style={at={(1,2/3)},anchor=west},
            every axis x label/.style={at={(ticklabel* cs:1.05)}, anchor=west,},
            every axis y label/.style={at={(ticklabel* cs:1.05)}, anchor=south,},
            domain=-pi:pi,samples=101]
                \addplot [blue,thick, domain = -pi:pi] {abs(sin(2*deg(x)))};
            \end{axis}

            \begin{axis}[ %Phase plot
            width = 5 in,
            height = 2.5 in,
            scale only axis,
            at={(0in,0in)},
            xtick={-pi, -(3/4)*pi,  -(1/2)*pi, -(1/4)*pi,  (1/4)*pi, (1/2)*pi, (3/4)*pi, pi},
            xticklabels={$-\pi$, $-\frac{3\pi}{4}$,  $-\frac{\pi}{2}$, $-\frac{\pi}{4}$,$\frac{\pi}{4}$,  $\frac{\pi}{2}$, $\frac{3\pi}{4}$, $\pi$},
            ytick={-pi, -(1/2)*pi, (1/2)*pi, pi},
            yticklabels={$-\pi$,  $-\frac{\pi}{2}$,  $\frac{\pi}{2}$,  $\pi$},
            xmin=-pi,xmax=pi,
            ymin=-pi,ymax=pi,
            axis lines=center,
            axis line style=->, xlabel = {$\omega$}, ylabel={$\angle H\left(e^{j\omega}\right)$},
            %every axis y label/.style={at={(0,1)},anchor=south},
            %every axis x label/.style={at={(1,2/3)},anchor=west},
            every axis x label/.style={at={(ticklabel* cs:1.05)}, anchor=west,},
            every axis y label/.style={at={(ticklabel* cs:1.05)}, anchor=south,}]
                \addplot[blue,thick,samples at={-2,-1,-1,0,0,1,1,2}]
                 ({x*pi/2},{int(\coordindex/2)==\coordindex/2?pi/2:-pi/2});
            \end{axis}
        \end{tikzpicture} 
    \end{figure}
\end{document}

在此处输入图片描述

如果你不想输入所有样本，请使用

    \addplot[blue,thick,samples at={-2,-1.5,...,2}]
             ({x*pi/2+(int(\coordindex/2)==\coordindex/2?0:pi/4)},{int(\coordindex/2)==\coordindex/2?pi/2:-pi/2});

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