Incremental orthogonal polynomial interpolation.

   [f, esys, eeval, edom] = interporthinc(x, fx, tol, inc)

   f = interporthinc(x, fx, tol, inc) interpolates an expression by using
   Chebyshev or Legendre points. In this version an incremental scheme is
   applied, and the interpolation degree is automatically found.

Inputs (required)
   x     = independent tau variavle (itau object).
   fx    = function (char).

Inputs (optional)
   tol   = tolerance for precicion (double). 
   inc   = step of polynomial degree (integer).

   f     = coeficients of interpolation (double vector).
   esys  = error in the linear system (double vector).
   eeval = (max.) error in the evaluation (double scalar).
   edom  = error in the full domain (double vector).

See also
  interporth, interporth2 and interporth2inc.