Syntax

   f = verapproximation(x, equation, a, step)

Description

   f = verapproximation(x, equation, a, step) evaluates the approximated 
   solution and compares it with the rhs.

Inputs

   x        = independent tau variable (itau object).
   equation = equation (char).
   a        = approximated coefficients (numeric vector).
   step     = evaluation step (double).

Output

   f        = error F(y_n(x))-f(x) (numeric vector).