将刻度标记定位在 pi/2 的整数倍处

Question

在我的代码中，我原本有

xtick={-2*pi, -(3/2)*pi, -(1/2)*pi, (1/2)*pi,(3/2)*pi, 2*pi},

在 $pi/2$ 的整数倍处放置刻度标记。它无法编译。我不得不用繁琐的十进制近似值代替它。为什么代码无法使用像 这样的表达式进行编译pi？为了指定环境中 x 轴的宽度axis，我使用了xmin=-2*pi,和xmax=2*pi,，为了指定余弦函数的定义域，我使用了domain=-2*pi:2*pi。

\documentclass{amsart}
\usepackage{mathtools}

\usepackage{tikz}
\usetikzlibrary{calc,angles,positioning,intersections,quotes,decorations.markings,backgrounds,patterns}

\usepackage{pgfplots}
\pgfplotsset{compat=1.11}



\begin{document}

\begin{tikzpicture}
\begin{axis}[width=4.5in,clip=false,
    xmin=-2*pi,xmax=2*pi,
    ymin=-1.25,ymax=1.25,
    axis lines=middle,
    %xtick={-2*pi, -(3/2)*pi, -pi, -(1/2)*pi, (1/2)*pi, pi, (3/2)*pi, 2*pi},
    xtick={-6.28318, -4.7123889, -3.14159, -1.5708, 1.5708, 3.14159, 4.7123889, 6.28318},
    xticklabel style={font=\footnotesize,fill=white},
    xticklabels={$-2\pi$,,$-\pi$,,,$\pi$,,$2\pi$},
    ytick={-1},
    yticklabel style={font=\footnotesize,fill=white},
    yticklabels={$-1$},
    extra y ticks={1},
    extra y tick labels={$1$},
    extra y tick style={yticklabel style={font=\footnotesize,fill=white,anchor=south east}},
    ticklabel style={font=\footnotesize,fill=white},
    axis line style={latex-latex},
    axis line style={shorten >=-7.5pt, shorten <=-7.5pt},
    xlabel style={at={(ticklabel* cs:1)},anchor=north west},
    ylabel style={at={(ticklabel* cs:1)},anchor=south west}
]

\addplot [samples=501,mark=none, thick, red,domain=-2*pi:2*pi] {cos(deg(x))};

\end{axis}
\end{tikzpicture}

\end{document}

Answer 1

随着 PGFPlots v1.16 的发布，现在可以在多个地方使用数学解析器。因此，您xtick现在可以使用提供的行...

% used PGFPlots v1.16
\documentclass[border=5pt]{standalone}
\usepackage{pgfplots}
\begin{document}
\begin{tikzpicture}
    \begin{axis}[
        xtick={-2*pi, -(3/2)*pi, -pi, -(1/2)*pi, (1/2)*pi, pi, (3/2)*pi, 2*pi},
%        xtick={-6.28318, -4.7123889, -3.14159, -1.5708, 1.5708, 3.14159, 4.7123889, 6.28318},
        xticklabel style={font=\footnotesize,fill=white},
        xticklabels={$-2\pi$,,$-\pi$,,,$\pi$,,$2\pi$},
        ytick={-1,1},
        axis lines=middle,
        domain=-2*pi:2*pi,
        samples=501,
        enlargelimits=true,
    ]
        \addplot [thick,red] {cos(deg(x))};
    \end{axis}
\end{tikzpicture}
\end{document}

Answer 2

\pgfmathparse可以通过或单独评估列表\pgfmathsetmacro。逗号列表将转换为数组，其中计算出的数字放在花括号中。因此，以下示例定义宏\ArrayToCommaList以再次获取逗号分隔的列表：

\documentclass{amsart}
\usepackage{mathtools}

\usepackage{tikz}
\usetikzlibrary{calc,angles,positioning,intersections,quotes,decorations.markings,backgrounds,patterns}

\usepackage{pgfplots}
\pgfplotsset{compat=1.11}

\makeatletter
\newcommand*{\ArrayToCommaList}[1]{%
  \let\ArrayToCommaList@Result\@empty
  \expandafter\@tfor\expandafter\ArrayToCommaList@Entry
  \expandafter:\expandafter=#1\do{%
    \edef\ArrayToCommaList@Result{%
      \ArrayToCommaList@Result,\ArrayToCommaList@Entry
    }%
  }%
  % Remove first comma
  \edef#1{%
    \expandafter\@cdr\ArrayToCommaList@Result\@empty\@nil
  }%
}
\makeatother

\begin{document}
\begin{tikzpicture}
\pgfmathsetmacro\xticklist{-2*pi, -(3/2)*pi, -pi, -(1/2)*pi,
  (1/2)*pi, pi, (3/2)*pi, 2*pi}
\ArrayToCommaList\xticklist
\begin{axis}[width=4.5in,clip=false,
    xmin=-2*pi,xmax=2*pi,
    ymin=-1.25,ymax=1.25,
    axis lines=middle,
    xtick=\xticklist,
    xticklabel style={font=\footnotesize,fill=white},
    xticklabels={$-2\pi$,,$-\pi$,,,$\pi$,,$2\pi$},
    minor x tick num=2,
    ytick={-1},
    yticklabel style={font=\footnotesize,fill=white},
    yticklabels={$-1$},
    extra y ticks={1},
    extra y tick labels={$1$},
    extra y tick style={yticklabel style={font=\footnotesize,fill=white,anchor=south east}},
    ticklabel style={font=\footnotesize,fill=white},
    axis line style={latex-latex},
    axis line style={shorten >=-7.5pt, shorten <=-7.5pt},
    xlabel style={at={(ticklabel* cs:1)},anchor=north west},
    ylabel style={at={(ticklabel* cs:1)},anchor=south west}
]

\addplot [samples=501,mark=none, thick, red,domain=-2*pi:2*pi] {cos(deg(x))};

\end{axis}
\end{tikzpicture}
\end{document}

Answer 3

运行xelatex

\documentclass{amsart}
\usepackage{pst-plot}    
\begin{document}

\psset{yunit=3}
\begin{pspicture}(-6.75,-1.3)(6.75,1.3)
\psframe*[linecolor=yellow!80!black!20](-6.7,-1.3)(6.7,1.3)
\psaxes[trigLabels,dx=3.14]{<->}(0,0)(-6.6,-1.25)(6.6,1.25)
\psplot[algebraic,linewidth=1.5pt,
        linecolor=red,plotpoints=1000]{-6.28}{6.28}{cos(x)}%
\end{pspicture}

\end{document}

每 pi/2 刻一次：

\psaxes[trigLabels,trigLabelBase=2,dx=1.57]{<->}(0,0)(-6.6,-1.25)(6.6,1.25)

Answer 4

\documentclass[12pt]{article}
\usepackage{pgf,tikz}
\usetikzlibrary{arrows}
\usepackage{mathrsfs}
\begin{document}
\begin{tikzpicture}[line cap=round,line join=round,>=triangle 45,x=1cm,y=1cm]
\draw[->,color=black] (-4.3,0.) -- (5.1,0.);
\draw[shift={(-3.14,0)},color=black] (0pt,2pt) -- (0pt,-2pt) node[below] {\footnotesize $-\pi$};
\draw[shift={(-1.6,0)},color=black] (0pt,2pt) -- (0pt,-2pt) node[below] {\footnotesize $-\pi/2$};
\draw[shift={(1.6,0)},color=black] (0pt,2pt) -- (0pt,-2pt) node[below] {\footnotesize $\pi/2$};
\draw[shift={(3.14,0)},color=black] (0pt,2pt) -- (0pt,-2pt) node[below] {\footnotesize $\pi$};
\draw[shift={(4.7,0)},color=black] (0pt,2pt) -- (0pt,-2pt) node[below] {\footnotesize $3\pi/2$};
\draw[->,color=black] (0.,-2.11) -- (0.,1.33);
\foreach \y in {-2.,-1.,1.}
\draw[shift={(0,\y)},color=black] (.5pt,0pt) -- (-.5pt,0pt) node[left] {\footnotesize $\y$};
\draw[color=black] (0pt,-10pt) node[right] {\footnotesize $0$};
\draw[line width=2.pt,color=magenta,smooth,samples=500,domain=-5:5] plot(\x,{cos(((\x))*180/pi)});
\begin{scriptsize}
\draw[color=magenta] (-4.6,.5) node {$f(x)=\cos x$};
\end{scriptsize}
\end{tikzpicture}
\end{document}