在 TIKZ 中绘制平方根的问题

Question

有人知道为什么这个图在 0 和 1 之间看起来很奇怪吗？如果我尝试绘制立方根函数，也会发生同样的情况。请指教。我试图避免使用 pgfplots 包。

\documentclass{article}
\usepackage{tikz}

\begin{document}
\begin{tikzpicture}[scale=.6,cap=round]
\tikzset{axes/.style={}}
  % The graphic
\draw[style=help lines,step=1cm, dotted] (-.5,-3.5) grid (10.5,5.5);
\begin{scope}[style=axes]
\draw[->] (-0.5,0) -- (10.5,0) node[right] {$x$};
\draw[->] (0,-3.5) -- (0,5.5) node[above] {$y$};
    \foreach \x/\xtext in {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
\draw[xshift=\x cm] (0pt,2.6pt) -- (0pt,-2.6pt) node[below,fill=white]
         {\scriptsize $\xtext$};
\foreach \y/\ytext in {-3, -2, -1,  1, 2, 3, 4, 5}
\draw[yshift=\y cm] (2.6pt,0pt) -- (-2.6pt,0pt) node[left,fill=white]
        {\scriptsize $\ytext$};
%\filldraw[blue] (0,0) circle (3pt) node[fill=white,below right=12pt] 
{\scriptsize $(0,0)$};
\filldraw[blue] (1,1) circle (3pt) node[fill=white,above=3pt] {\scriptsize 
$(1,1)$};
\filldraw[blue] (3,1.732) circle (3pt) node[fill=white,below=3pt] 
 {\scriptsize $(3,\sqrt{3})$};
\filldraw[blue] (4,2) circle (3pt) node[fill=white,above=3pt] {\scriptsize 
$(4,2)$};
\filldraw[blue] (9,3) circle (3pt) node[fill=white,above=3pt] {\scriptsize 
$(9,3)$};
\draw[domain=0:10,smooth,variable=\x,blue,thick,->] plot ({\x},{(\x)^.5});
\end{scope}
\end{tikzpicture}


\end{document}

Answer 1

因为您的样本不够大：默认情况下是 25 个点。如果样本为 200 个点，则此方法有效。

编辑：修改示例。非常感谢 Skillmon 提出修改示例的想法，也感谢 @marmot 给出一个简单有效的示例。

你的\foreach循环不需要有两个变量。只需要一个就足够了，为了让显示的文本更小，这就是关键font=\scriptsize。

编辑2： 为了避免对每个节点重复此操作，只需every node/.style={font=\scriptsize}覆盖预先存在的样式或every node/append style={font=\scriptsize}简单地将此样式添加到预先存在的样式而不覆盖它。

\documentclass{article}
\usepackage{tikz,pgfplots}
\begin{document}
\begin{tikzpicture}[scale=.6,cap=round,every node/.style={font=\scriptsize}]
\tikzset{axes/.style={}}
  % The graphic
\draw[style=help lines,step=1cm, dotted] (-.5,-3.5) grid (10.5,5.5);
\begin{scope}[style=axes]
\draw[->] (-0.5,0) -- (10.5,0) node[right] {$x$};
\draw[->] (0,-3.5) -- (0,5.5) node[above] {$y$};
    \foreach \x in {1, ..., 10}
\draw[xshift=\x cm] (0pt,2.6pt) -- (0pt,-2.6pt) node[below,fill=white]
         { \x};
\foreach \y in {-3,..., 5}
\draw[yshift=\y cm] (2.6pt,0pt) -- (-2.6pt,0pt) node[left,fill=white]
        { \y};

\filldraw[blue] (0,0) circle (3pt) node[fill=white,below right=12pt] 
{$(0,0)$};
\filldraw[blue] (1,1) circle (3pt) node[fill=white,above=3pt] {
$(1,1)$};
\filldraw[blue] (3,1.732) circle (3pt) node[fill=white,below=3pt] 
 {$(3,\sqrt{3})$};
\filldraw[blue] (4,2) circle (3pt) node[fill=white,above=3pt] {
$(4,2)$};
\filldraw[blue] (9,3) circle (3pt) node[fill=white,above=3pt] {
$(9,3)$};
\draw[domain=0:10,smooth,variable=\x,blue,thick,->,samples at={0,0.05,...,1,1.5,...,10.5}] plot ({\x},{(\x)^.5});
\end{scope}
\end{tikzpicture}
\end{document}

Answer 2

@AndréC 答案的一个小变化（+1）：再循环一次，计算标记位置，......

\documentclass{article}
\usepackage{tikz}

\begin{document}
    \begin{tikzpicture}[scale=.6,
every node/.append style = {font=\scriptsize, inner sep=2pt, xscale=0.9}
                        ]
% grid
\draw[help lines,dotted] (0,-3.5) grid (10.5,5.5);
% axis
\draw[->] (-0.4,0) -- (10.5,0) node[right] {$x$};
\draw[->] (0,-3.5) -- ( 0,5.5) node[above] {$y$};
\foreach \x in {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}
    \draw (\x,2pt) -- + (0,-4pt) node[below,fill=white] {\x};
\foreach \y in {-3,...,5}
    \draw (2pt,\y) -- + (-4pt,0) node[left, fill=white] {\y};
% curve
\draw[smooth, blue,thick,->]
    plot[samples at={0,0.05,...,1,1.5,...,10.5}] (\x,\x^.5);
% marks
\foreach \i/\j in {0/0, 1/1, 3/$\sqrt{3}$, 4/2, 9/3}
{   \pgfmathparse{sqrt(\i)}
    \fill[blue]  (\i,\pgfmathresult)
        circle[radius=2pt] \ifnum\i>0 node[above=1pt] {(\i,\j)}\fi;
}
    \end{tikzpicture}
\end{document}