Functional analysis-- Mathematics 192 Functional analysis 183 Operational calculus-- Functional analysis-- Mathematics 109 Special functions-- Analysis-- Mathematics 61 Mathematics 35 Functional Analysis 22 Functions of real variables 13 Measure theory 13 Operator theory 11 Differential equations, Partial 8 MATHEMATICS / Functional Analysis 8 Congresses 6 Nonlinear functional analysis 6 Topology 6 Approximation theory 5 Functions of complex variables 5 Mathematical optimization 5 Operational calculus; Functional analysis; Mathematics 5 Theory of distributions (Functional analysis) 5 Banach spaces 4 Calculus 4 Functional analysis -- Instructional exposition (textbooks, tutorial papers, etc.) 4 Functions 4 Linear topological spaces 4 Mathematical analysis 4 Special functions; Analysis; Mathematics 4 Algebra 3 Control theory 3 Groupoids 3 Harmonic analysis 3