更新

Question

我有正弦波，想在上面画一个电波纹，所以我用装饰选项画了一条锯齿线。但是锯齿线的方向与波成直角。我需要一条沿着正弦波方向的锯齿线，方向为 x 轴。这就是我所得到的：

\documentclass{beamer}
\usepackage{lmodern}
\usepackage{tikz}
\usetikzlibrary{decorations.pathmorphing}

\tikzset{snake it/.style={decorate, decoration=snake}}

\newcommand{\drawCoordinateSystem}[2]{
        \draw[color=#1, step=.5cm, very thin] (0,-2) grid (7.5,2);
        \draw [#2, thick, ->] (0,0) -- (8,0) node[right]{$T$}; 
        \draw [#2, thick, <->](0,2.5) -- (0,-2.5) node[above] {$F$};
    }%\end{tikzpicture}%end newCommand

\begin{document}
\vspace*{2cm}
\begin{center}

    \begin{tikzpicture}[scale=0.8]  
        \drawCoordinateSystem{lightgray}{black}         
         \draw[domain=0:6.5, black, thick]   plot (\x,{sin(\x r)})   node[right, above,] {$I$};         
         \draw[decorate, decoration={zigzag,segment length = .15cm, amplitude = 1.5mm}, domain=0:6.5, thick] plot (\x,{sin(\x r)});             
    \end{tikzpicture}
\end{center}
\end{document}

这就是我所需要的：

有人能帮我解决这个问题吗？

Answer 1

我猜测“波纹”是另一个频率更高的正弦波，添加到主正弦波中，因此您可以将其绘制为第一个函数之上的另一个函数。

我不得不删除r（弧度）并调整数字，以避免溢出错误（“数字太大”）。

\documentclass{beamer}
\usepackage{lmodern}
\usepackage{tikz}

\newcommand{\drawCoordinateSystem}[2]{
        \draw[color=#1, step=.5cm, very thin] (0,-2) grid (7.5,2);
        \draw [#2, thick, ->] (0,0) -- (8,0) node[right]{$T$}; 
        \draw [#2, thick, <->](0,2.5) -- (0,-2.5) node[above] {$F$};
    }%\end{tikzpicture}%end newCommand

\begin{document}
\vspace*{2cm}
\begin{center}

    \begin{tikzpicture}[scale=0.8]  
        \drawCoordinateSystem{lightgray}{black}         
         \draw[domain=0:6.5, black, thick]   plot (\x,{sin(\x*60.0)})   node[right, above,] {$I$};         
         %\draw[decorate, decoration={zigzag,segment length = .15cm, amplitude = 1.5mm}, domain=0:6.5, thick] plot (\x,{sin(\x r)});             
        \draw[domain=0:6.4, black, thick, samples=200]   plot (\x,{sin(\x*60.0)+0.5*sin(\x*960.0});     

    \end{tikzpicture}
\end{center}
\end{document}

更新

如果您的波纹必须更加“三角”，那么您可以作弊并减少样本数量。如果您选择得当，您可以仅在其峰值处对正弦噪声进行采样，从而获得三角波。例如：

\begin{tikzpicture}[scale=0.8]  
    \drawCoordinateSystem{lightgray}{black}         
     \draw[domain=0:6.5, black, thick]   plot (\x,{sin(\x*60.0)})   node[right, above,] {$I$};         
    \draw[domain=0:6.45, black, thick, samples=87]   plot (\x,{sin(\x*60.0)+0.5*sin(\x*1200.0});     
\end{tikzpicture}

生成：