方程式中的对齐

方程式中的对齐

我想把两个简单的等式一个接一个地写在下方,但是对齐环境似乎向右对齐,而我想将它们向左对齐。代码如下:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{equation*}
\begin{aligned}
S_1' (x_0) = S_n' (x_n) = 0 \quad \text{(clamped boundary conditions),} \quad \text{or} \\
S_1'' (x_0) = S_n'' (x_n) = 0 \quad \text{(natural boundary conditions)}
\end{aligned}
\end{equation*}

\end{document}

产生

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但我希望它S_1''(x_0)直接出现在下方S_1'(x_0),而不是移动到左侧。您知道解决办法吗?

答案1

如果要将材料左对齐,则需要通过&符号提供对齐点。

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\documentclass{article}
\usepackage{amsmath} % for 'align*' environment

\begin{document}

\begin{align*}
&S_1' (x_0) = S_n' (x_n) = 0 \quad \text{(clamped boundary conditions), or} \\
&S_1'' (x_0) = S_n'' (x_n) = 0 \quad \text{(natural boundary conditions)}
\end{align*}

\end{document}

答案2

比对点用 标记&。如果存在多个组(比对列),则进一步&使用 来引入每个新组(第一组除外),因此 n 列比对需要 2n-1 个与号。

例如,您可以使用此代码:

\documentclass{article}

\usepackage{amsmath}

\begin{document}

\begin{align*} 
S_1' (x_0) &= S_n' (x_n) = 0 &&\text{(clamped boundary conditions),} \quad \text{or} \\
S_1'' (x_0) &= S_n'' (x_n) = 0 && \text{(natural boundary conditions)}
\end{align*} 

\end{document}

我还建议根据这些解决方案alignat*,使用\ArrowBetweenLines来自的命令mathtools(在这种情况下无需加载amsmath),或者flalign*

\documentclass{article}

\usepackage{mathtools}

\begin{document}


\begin{alignat*}{3}
 & & S_1' (x_0) &= S_n' (x_n) = 0 &\quad & \text{(clamped boundary conditions),} \\
\ArrowBetweenLines[\text{or}]%
 & & S_1'' (x_0) &= S_n'' (x_n) = 0 & & \text{(natural boundary conditions)}
 \end{alignat*}

\begin{flalign*} 
& & S_1' (x_0) &= S_n' (x_n) = 0 &&\text{(clamped boundary conditions),} \\
& \text{or} & S_1'' (x_0) &= S_n'' (x_n) = 0 && \text{(natural boundary conditions)} 
\end{flalign*}

\end{document}

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答案3

您忘记了对齐锚点(&符号):

\documentclass{article}
\usepackage{amsmath}

\begin{document}

\begin{equation*}
\begin{aligned}
S_1' (x_0)  & = S_n' (x_n) = 0 \quad \text{(clamped boundary conditions),} \quad \text{or} \\
S_1'' (x_0) & = S_n'' (x_n) = 0 \quad \text{(natural boundary conditions)}
\end{aligned}
\end{equation*}

\end{document}

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