41A10
| Approximation by polynomials {For approximation by trigonometric polynomials, see 42A10}
| 41A15
Spline approximation
41A17
| Inequalities in approximation (Bernstein, Jackson, Nikol\cprime ski\u\i-type inequalities)
| 41A20
Approximation by rational functions
41A21
| Padé approximation
| 41A25
| Rate of convergence, degree of approximation
| 41A27
Inverse theorems
41A28
| Simultaneous approximation
| 41A29
Approximation with constraints
41A30
Approximation by other special function classes
41A35
Approximation by operators (in particular, by integral operators)
41A36
Approximation by positive operators
41A40
Saturation
41A44
Best constants
41A45
Approximation by arbitrary linear expressions
41A46
| Approximation by arbitrary nonlinear expressions; widths and entropy
| 41A50
Best approximation, Chebyshev systems
41A52
Uniqueness of best approximation
41A55
Approximate quadratures
41A58
Series expansions (e.g. Taylor, Lidstone series, but not Fourier series)
41A60
| Asymptotic approximations, asymptotic expansions (steepest descent, etc.) [See also 30E15]
| 41A63
Multidimensional problems (should also be assigned at least one other classification number in this section)
41A65
Abstract approximation theory (approximation in normed linear spaces and other abstract spaces)
41A80
Remainders in approximation formulas
41A99
| Miscellaneous topics
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |