interpolate - function or expression interpolation (rheolef-7.2)

       Pierre  Saramito  <Pierre.Saramito@imag.fr>

       Copyright   (C)  2000-2018  Pierre  Saramito  <Pierre.Saramito@imag.fr> GPLv3+: GNU GPL version 3 or
       later  <http://gnu.org/licenses/gpl.html>.  This  is  free  software:  you  are free to change and
       redistribute it.  There is NO WARRANTY, to the extent permitted by law.

rheolef                                            Version 7.2                             interpolate(3rheolef)

       The interpolation function implements the usual Lagrange interpolation of a function or a class-function
       on a finite element space(2).

       It is possible to interpolate an expression involving a combination of functions, class-functions and
       fields:

           field vh = interpolate (Xh, sqrt(uh) + 2*max(0.,uh));

       This documentation has been generated from file main/lib/interpolate.h

       The implementation of expressions bases on the expression template and SFINAE C++ idioms.

       interpolate - function or expression interpolation (rheolef-7.2)

       The reinterpolation of a field on another mesh or on another finite element space is also possible:

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

        Such a reinterpolation is very frequent in mesh adaptive loops.

           template <class Expression>
           field interpolate (const space& Xh, const Expression& expr);

        Example The following code compute the Lagrange interpolation pi_h_u the function u(x):

          Float u(const point& x) { return exp(x[0]*x[1]); }
          ...
          geo omega('square');
          space Xh (omega, 'P1');
          field pi_h_u = interpolate (Xh, u);