Approximations and Expansions Mathematics 27 Differential equations, partial 11 Partial Differential Equations 10 Applications of Mathematics 7 Fourier Analysis 7 Fourier analysis 7 more ... Functional Analysis 7 Functional analysis 7 Differential Equations 5 Ordinary Differential Equations 5 Analysis 4 Global analysis (Mathematics) 4 Functions of a Complex Variable 3 Functions of complex variables 3 Functions, special 3 Numerical Analysis 3 Numerical analysis 3 Several Complex Variables and Analytic Spaces 3 Special Functions 3 Abstract Harmonic Analysis 2 Algorithms 2 Approximation theory 2 Computer vision 2 Harmonic analysis 2 Mathematical optimization 2 Number Theory 2 Number theory 2 Operator Theory 2 Operator theory 2 less ...