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使用 \foreach 和椭圆方向时出错

tag-icon • tag-icon tikz-pgf foreach
使用 \foreach 和椭圆方向时出错

下面这行

\foreach \x / \y in {0.422201/1.000000,1.000000/2.368540}
  {\draw[very thin] (0,0) ellipse (\x and \y)};

给出

ERROR: Package PGF Math Error: Unknown operator `a' or `an' (in '0.422201and 1.000000').

然后我尝试了一下，(\x{} and \y)因为它看起来像是一个空间问题，但它也不起作用。

ERROR: Undefined control sequence.

--- TeX said ---
\pgfmath@dimen@ ...men@@ #1=0.0pt\relax \pgfmath@ 

l.10 ...aw[very thin] (0,0) ellipse (\x{} and \y)}

这是文档

\documentclass{article}
\usepackage{tkz-euclide}
\begin{document}

\begin{tikzpicture}
  \begin{scope}
    \clip (-1.5,-1.5) rectangle (4,4);
    \begin{scope}[rotate=12.549]
      \foreach \x / \y in {0.422201/1.000000,1.000000/2.368540}
        {\draw[very thin] (0,0) ellipse (\x and \y)};
      % \draw[very thin] (0,0) ellipse (0.422201 and 1.000000);
      % \draw[very thin] (0,0) ellipse (1.000000 and 2.368540);
      \draw[very thin] (0,0) ellipse (1.349721 and 3.196868);
      \draw[very thin] (0,0) ellipse (1.625882 and 3.850967);
      \draw[very thin] (0,0) ellipse (1.861515 and 4.409073);
      \draw[very thin] (0,0) ellipse (2.070504 and 4.904071);
    \end{scope}
  \end{scope}
\end{tikzpicture}

\end{document}

以及预期结果

同心椭圆

答案1

您必须将\xand括\y在括号内（最好是安全的），因为后面的空格\x会被吞掉，从而形成0.422201and。此外，您必须将;右括号放在

  {\draw[very thin] (0,0) ellipse ({\x} and {\y});}

用这些，

\documentclass{article}
\usepackage{tkz-euclide}
\begin{document}

\begin{tikzpicture}
  \begin{scope}
    \clip (-1.5,-1.5) rectangle (4,4);
    \begin{scope}[rotate=12.549]
      \foreach \x / \y in {0.422201/1,1/2.368540,1.349721/3.196868,1.625882/3.850967,1.861515/4.409073,2.070504/4.904071}
        {\draw[very thin] (0,0) ellipse ({\x} and {\y});
        }      
    \end{scope}
  \end{scope}
\end{tikzpicture}

\end{document}

在此处输入图片描述

答案2

您可以使用省略号的替代语法：

% arara: pdflatex

\documentclass{article}
\usepackage{tikz}

\begin{document}    
\begin{tikzpicture}
    \begin{scope}
        \clip (-1.5,-1.5) rectangle (4,4);
        \begin{scope}[rotate=12.549]
            \foreach \x/\y in {0.422201/1.000000,1.000000/2.368540,1.349721/3.196868,1.625882/3.850967,1.861515/4.409073,2.070504/4.904071}
            \draw[very thin] (0,0) ellipse [x radius=\x,y radius=\y];
        \end{scope}
    \end{scope}
\end{tikzpicture}
\end{document}

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