R help - Jun 2004 - nonlinear modeling with rational functions?

Rational functions (ratios of polynomials) often provide good 
approximations to many functions.  Does anyone know of any literature on 
nonlinear modeling with rational functions, sequential estimation, 
diagnostics, etc.?  I know I can do it with "nls" and other nonlinear 
regression functions, but I'm wondering what literature might exist 
discussing how a search for an appropriate rational approximation? 

      Thanks,
      Spencer Graves

On Wed, Jun 16, 2004 at 10:28:39AM -0500, Spencer Graves wrote:
>      Rational functions (ratios of polynomials) often provide good 
> approximations to many functions.  Does anyone know of any literature on 
> nonlinear modeling with rational functions, sequential estimation, 
> diagnostics, etc.?  I know I can do it with "nls" and other
nonlinear
> regression functions, but I'm wondering what literature might exist 
> discussing how a search for an appropriate rational approximation? 
The book

@Book{judd98,
  author =       {Judd, Kenneth L},
  title =        {Numerical methods in economics},
  publisher =    {MIT Press},
  year =         1998
}

provides some information about constructing rational approximations
(aka Pad?? approximations) for functions with known algebraic forms,
but not for the estimation from data.

However, the text has some references, in particular

Cuyt, A and L Wuytack. 1986. Nonlinear Numerical Methods: Theory and
Practice. Amsterdam: North-Holland

which you might find helpful.

Best,

Tamas

-- 
Tam??s K. Papp
E-mail: tpapp at axelero.hu
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