A short story about the origins of Magnus Expansion, why we got involved and how it led us to meet Geometric Integration. We present a biographical draft of Wilhelm Magnus, a sketchy discussion of what is the expansion which carries his name and a derivation of the formalism equations. We explain the important feature that makes the expansion an appropriate tool to develop Geometric Integration schemes.

中文翻译：

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为什么 Magnus 展开

一个关于 Magnus Expansion 起源的短篇小说，我们为何参与其中，以及它如何让我们遇到几何积分。我们提供了威廉·马格努斯的传记草稿，粗略地讨论了以他的名字命名的扩展是什么以及形式主义方程的推导。我们解释了使扩展成为开发几何积分方案的适当工具的重要特征。