In the waveguide problems of this paper, results obtained cannot be directly found in the existing literature and have been worked out from fundamental theory of differential equations.
在本文所讨论的波导问题中，所得结果不能直接从现有文献中导出。我们已经从基本微分方程理论中算出了这些结果。
Many of the fundamental laws of physics, chemistry, biology, and economics can be formulated as differential equations.
许多物理，化学，生物学的基本法律，经济问题都可归结为微分方程。
In particular, the course focuses on physically-arising partial differential equations, with emphasis on the fundamental ideas underlying various methods.
值得一提的是，该课程在著重于物理相关的偏微分方程，同时也注意各种方法背后所隐含的基本概念。
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