42-XX Fourier analysis
42-00 General reference works (handbooks, dictionaries, bibliographies, etc.)
42-01 Instructional exposition (textbooks, tutorial papers, etc.)
42-02 Research exposition (monographs, survey articles)
42-03 Historical {!must also be assigned at least one classification number from section 01}
42-04 Explicit machine computation and programs (not the theory of computation or programming)
42-06 Proceedings, conferences, collections, etc.
42Axx Fourier analysis in one variable
42A05 Trigonometric polynomials, inequalities, extremal problems
42A10 Trigonometric approximation
42A15 Trigonometric interpolation
42A16 Fourier coefficients, Fourier series of functions with special properties, special Fourier series {For automorphic theory, see mainly 11F30}
42A20 Convergence and absolute convergence of Fourier and trigonometric series
42A24 Summability and absolute summability of Fourier and trigonometric series
42A32 Trigonometric series of special types (positive coefficients, monotonic coefficients, etc.)
42A38 Fourier and Fourier - Stieltjes transforms and other transforms of Fourier type
42A45 Multipliers
42A50 Conjugate functions, conjugate series, singular integrals
42A55 Lacunary series of trigonometric and other functions; Riesz products
42A61 Probabilistic methods
42A63 Uniqueness of trigonometric expansions, uniqueness of Fourier expansions, Riemann theory, localization
42A65 Completeness of sets of functions
42A70 Trigonometric moment problems
42A75 Classical almost periodic functions, mean periodic functions [See also 43A60]
42A82 Positive definite functions
42A85 Convolution, factorization
42A99 None of the above, but in this section
42Bxx Fourier analysis in several variables {For automorphic theory, see mainly 11F30}
42B05 Fourier series and coefficients
42B08 Summability
42B10 Fourier and Fourier - Stieltjes transforms and other transforms of Fourier type
42B15 Multipliers
42B20 Singular integrals (Caldersn - Zygmund, etc.)
42B25 Maximal functions, Littlewood - Paley theory
42B30 Hp-spaces
42B35 Function spaces arising in harmonic analysis
42B99 None of the above, but in this section
42Cxx Nontrigonometric Fourier analysis
42C05 Orthogonal functions and polynomials, general theory [See also 33C45, 33C50, 33D45]
42C10 Fourier series in special orthogonal functions (Legendre polynomials, Walsh functions, etc.)
42C15 Series of general orthogonal functions, generalized Fourier expansions, nonorthogonal expansions
42C20 Rearrangements and other transformations of Fourier and other orthogonal series
42C25 Uniqueness and localization for orthogonal series
42C30 Completeness of sets of functions
42C40 Wavelets
42C99 None of the above, but in this section