具有 svmult 和 subequations 环境的奇怪垂直空间

Question

当使用类 svmult 和 amsmath 中的环境子方程时，使用 \label 命令时，文本和公式之间会插入难看的垂直空格。将子方程环境移动到某些文本前面会导致换行。

\documentclass{svmult}
\usepackage{amsmath}
\begin{document}
  Some text. 
  \begin{subequations}
    \label{eq:NNMex1Ham}
%Moving the \label command to a previous line, introduces a line breaks.
  We consider the resonant oscillator
  \begin{align}
    \ddot{x}_1 + x_1 + x_1^3 + K (x_1-x_2)^3 &= 0,\\
    \ddot{x}_2 + x_2 + x_2^3 + K (x_2-x_1)^3 &= 0,
  \end{align}
  \end{subequations}
  which will occur also in the next chapter.
  

  We consider the resonant oscillator
    \begin{subequations}
    \label{eq:NNMex1Ham2}
  \begin{align}
    \ddot{x}_1 + x_1 + x_1^3 + K (x_1-x_2)^3 &= 0,\\
    \ddot{x}_2 + x_2 + x_2^3 + K (x_2-x_1)^3 &= 0,
  \end{align}
  \end{subequations}
  which will occur also in the next chapter.

  %Now the environment without a \label command
  We consider the resonant oscillator
    \begin{subequations}
  \begin{align}
    \ddot{x}_1 + x_1 + x_1^3 + K (x_1-x_2)^3 &= 0,\\
    \ddot{x}_2 + x_2 + x_2^3 + K (x_2-x_1)^3 &= 0,
  \end{align}
  \end{subequations}
  which will occur also in the next chapter. 
\end{document}

在一个非常相似的问题的答案中找到的解决方案\AtBeginEnvironment{subequations}{\ifhmode\unskip\fi}也解决了该问题，但在当前情况下无法应用：我是作者之一，无权访问编辑器的样式文件或标题行。