Approximation theory 52 Approximations -- expansions-- Mathematics 18 Mathematics 6 Numerical analysis 6 Functional analysis 4 Mathematical optimization 4 Asymptotic expansions 3 Calculus 3 Computer algorithms 3 Fourier analysis 3 Functions of complex variables 3 Interpolation 3 Multivariate analysis 3 Numerical solutions 3 Operator theory 3 Polynomials 3 Spline theory 3 Approximations and expansions 2 Computational complexity 2 Computer science 2 Congresses 2 Data processing 2 Differential equations 2 Functions 2 Functions of a complex variable 2 Fuzzy logic 2 Harmonic analysis on Euclidean spaces 2 Information theory 2 Linear operators 2 Mathematical models 2