如何减少阵列环境的尺寸？

Question

我的代码是

\[
    D_{k+1}(x_{k+1}) = \min_{\begin{array}{c}
    \text{all } x_k \text{ such that}\\
    p_{{x_k}{x_{k+1}}} > 0
    \end{array}}
    \left[ D_k(x_k)-\ln\left(p_{{x_{k-1}}{x_k}}
    r\left(z_k; x_{k-1}, x_k\right)\right) \right]
\]

不过，我想把它做得all x_k such that p_{{x_k}{x_{k+1}} > 0小一点。

我怎样才能减小该部分的尺寸？

Answer 1

您可以使用包\substack的宏amsmath。与示例中使用的方法相比array， 的参数中的材料\substack会自动设置在 中\scriptstyle。另外，请将“such that”缩写为“st”。

\documentclass{article}
\usepackage{amsmath} % for \text and \substack macros
\begin{document} 
\[
    D_{k+1}(x_{k+1}) = \min_{%
    \substack{\text{all $x_k$ s.t.} \\[0.25ex] 
              p_{x_k x_{k+1}} > 0}}
    \bigl[ D_k(x_k)-\ln\bigl(p_{x_{k-1} x_k}
    r(z_k; x_{k-1}, x_k)\bigr) \bigr]
\]
\end{document}