Characterization of an extremal sum of ridge functions

  • Authors:
  • Vugar E. Ismailov

  • Affiliations:
  • Mathematics and Mechanics Institute, Azerbaijan National Academy of Sciences, Az-1141, Baku, Azerbaijan

  • Venue:
  • Journal of Computational and Applied Mathematics
  • Year:
  • 2007

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Abstract

The approximation problem considered in the paper is to approximate a continuous multivariate function f(x)=f(x"1,...,x"d) by sums of two ridge functions in the uniform norm. We give a necessary and sufficient condition for a sum of two ridge functions to be a best approximation to f(x). This main result is next used in a special case to obtain an explicit formula for the approximation error and to construct one best approximation. The problem of well approximation by such sums is also considered.