Differential equations, Linear Differential equations 5 Differential equations, Partial 4 Fourier transformations 3 Algebras, Linear 2 Asymptotic theory 2 Numerical solutions 2 Boundary value problems 1 Congresses 1 Difference equations 1 Differential equations, Nonlinear 1 Evolution equations 1 Finite element method 1 Fourier analysis 1 Functional analysis 1 Functional analysis -- Instructional exposition (textbooks, tutorial papers, etc.) 1 Group theory 1 History 1 Mathematical physics 1 Mechanics 1 Partial differential equations -- Instructional exposition (textbooks, tutorial papers, etc.) 1 Power series 1 System analysis 1 Transformations (Mathematics) 1 WKB approximation 1 Water waves 1