41-XX Approximations and expansions {For numerical approximation, see 65Dxx}

• 41A15 Spline approximation
  
• 41A40 Saturation
  
• 41A46 Approximation by arbitrary nonlinear expressions; widths and entropy
  
• 41A55 Approximate quadratures
  
• 41A63 Multidimensional problems (should also be assigned at least one other classification number in this section)