## 41-XX | 40 | Top | 42 |

41-00 | General reference works (handbooks, dictionaries, bibliographies, etc.) |

41-01 | Instructional exposition (textbooks, tutorial papers, etc.) |

41-02 | Research exposition (monographs, survey articles) |

41-03 | Historical (must also be assigned at least one classification number from Section 01) |

41-04 | Explicit machine computation and programs (not the theory of computation or programming) |

41-06 | Proceedings, conferences, collections, etc. |

41A05 | Interpolation [See also 42A15 and 65D05] |

41A10 | Approximation by polynomials {For approximation by trigonometric polynomials, see 42A10} |

41A15 | Spline approximation |

41A17 | Inequalities in approximation (Bernstein, Jackson, Nikoľskii-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 |