NAME

       interpolate - Lagrange interpolation of a function

DESCRIPTION

        The function interpolation implements the
        Lagrange interpolation of a function or a class-function.

SYNOPSYS

        template <class Function>
        field interpolate (const space& Xh, const Function& f);

EXAMPLE

        The following code compute the Lagrange interpolation
        pi_h_u of u(x).

         Float u(const point& x);
         ...
         geo omega("square");
         space Xh (omega, "P1");
         field pi_h_u = interpolate (Xh, u);

ADVANCED EXAMPLE

       It  is possible the replace the function u by a variable of the field type that represents
       a picewise polynomial function: this invocation allows the reinterpolation of a  field  on
       another mesh or with another approximation.

         geo omega2 ("square2");
         space X2h (omega2, "P1");
         field uh2 = interpolate (X2h, pi_h_u);