41-XX Approximations and expansions {For approximation theory in the complex domain, see 30E05, 30E10; for trigonometric approximation and interpolation, see 42A10, 42A15; for numerical approximation, see 65Dxx} 59127

41Axx Approximations and expansions {For approximation theory in the complex domain, see 30E05, 30E10; for trigonometric approximation and interpolation, see 42A10, 42A15; for numerical approximation, see 65Dxx} 58079

41A60 Asymptotic approximations, asymptotic expansions (steepest descent, etc.) [See also 30E15] 3671

41A63 Multidimensional problems [Should also be assigned at least one other classification number from Section 41-XX] 4868

41A65 Abstract approximation theory (approximation in normed linear spaces and other abstract spaces) 6295