如何制作循环？

Question

我需要在 LaTeX 中模拟 for 循环。我的代码如下

\documentclass[9pt]{article}
\usepackage{tikz}
\usepackage{pgfplots}
\begin{document}

\begin{tikzpicture}[scale=1.2, font=\tiny] 
\begin{axis}[
    axis x line=middle,         
    axis y line=middle,         
    domain=-5:5,                
    restrict y to domain=-5:5,  
    xmin=-5,    xmax=5,         
    ymin=-5,    ymax=5,         
    x=0.5cm,                        
    y=0.5cm,                        
    grid=both,                  
    xtick={-5,...,5},           
    ytick={-5,...,5},           
    xlabel=$x$,
    ylabel=$y$,
    every axis x label/.style={
    at={(ticklabel* cs:1)},
    anchor=west,},
    every axis y label/.style={
    at={(ticklabel* cs:1)},
    anchor=south,},
]
\addplot[smooth,red,domain=0:2*pi,variable=\t] ({4*cos(180/pi*t)},{4*sin(180/pi*t)});
\addplot[smooth,orange,domain=0:4,variable=\r] ({r*cos(360/4)},{r*sin(360/4)});
\addplot[smooth,orange,domain=0:4,variable=\r] ({r*cos(2*360/4)},{r*sin(2*360/4)});
\addplot[smooth,orange,domain=0:4,variable=\r] ({r*cos(3*360/4)},{r*sin(3*360/4)});
\end{axis}
\end{tikzpicture}
\end{document}

是否可以编写 for 循环来自动生成“n”行？

Answer 1

使用两个嵌套\foreach循环。由于\k取决于，\n您可能可以将其减少到一个循环。我不是数学家，但我认为这里的 TeX 部分是正确的。

\documentclass[9pt]{article}
\usepackage{tikz,pgfplots}

\newcommand{\nMAX}{20} 
\newcommand{\kMAX}{19}

\begin{document}
\begin{tikzpicture}[scale=1.2, font=\tiny] 
\begin{axis}[
    axis x line=middle,         
    axis y line=middle,         
    domain=-5:5,                
    restrict y to domain=-5:5,  
    xmin=-5,    xmax=5,         
    ymin=-5,    ymax=5,         
    x=0.5cm,                        
    y=0.5cm,                        
    grid=both,                  
    xtick={-5,...,5},           
    ytick={-5,...,5},           
    xlabel=$x$,
    ylabel=$y$,
    every axis x label/.style={
    at={(ticklabel* cs:1)},
    anchor=west,},
    every axis y label/.style={
    at={(ticklabel* cs:1)},
    anchor=south,},
]

\foreach \n in {1, ..., \nMAX} 
    \foreach \k in {0, ..., \kMAX} 
        {
            \addplot[smooth,orange,domain=0:4,variable=\r]
                ({r*cos(\k*360/\n)},{r*sin(\k*360/\n)});
        }

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

这是你所期待的吗？