/*===========================================================================

 Copyright (C) 2002-2020 Yves Renard, Julien Pommier.

 This file is a part of GetFEM

 GetFEM  is  free software;  you  can  redistribute  it  and/or modify it
 under  the  terms  of the  GNU  Lesser General Public License as published
 by  the  Free Software Foundation;  either version 3 of the License,  or
 (at your option) any later version along with the GCC Runtime Library
 Exception either version 3.1 or (at your option) any later version.
 This program  is  distributed  in  the  hope  that it will be useful,  but
 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
 or  FITNESS  FOR  A PARTICULAR PURPOSE.  See the GNU Lesser General Public
 License and GCC Runtime Library Exception for more details.
 You  should  have received a copy of the GNU Lesser General Public License
 along  with  this program;  if not, write to the Free Software Foundation,
 Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301, USA.

===========================================================================*/

/**
 * Linear Elastostatic problem with a crack.
 *
 * This program is used to check that getfem++ is working. This is also
 * a good example of use of GetFEM.
*/

#include "getfem/getfem_assembling.h" /* import assembly methods (and norms comp.) */
#include "getfem/getfem_export.h"   /* export functions (save solution in a file)  */
#include "getfem/getfem_derivatives.h"
#include "getfem/getfem_regular_meshes.h"
#include "getfem/getfem_model_solvers.h"
#include "getfem/getfem_mesh_im_level_set.h"
#include "getfem/getfem_mesh_fem_level_set.h"
#include "getfem/getfem_mesh_fem_product.h"
#include "getfem/getfem_mesh_fem_global_function.h"
#include "getfem_spider_fem.h"
#include "getfem/getfem_mesh_fem_sum.h"
#include "gmm/gmm.h"
#include "getfem/getfem_error_estimate.h"
#include <sstream>
#include "getfem/getfem_interpolated_fem.h"

using std::endl; using std::cout; using std::cerr;
using std::ends; using std::cin;


/* some GetFEM types that we will be using */
using bgeot::base_small_vector; /* special class for small (dim<16) vectors */
using bgeot::base_node;  /* geometrical nodes(derived from base_small_vector)*/
using bgeot::scalar_type; /* = double */
using bgeot::size_type;   /* = unsigned long */
using bgeot::short_type;
using bgeot::dim_type;
using bgeot::base_matrix; /* small dense matrix. */

/* definition of some matrix/vector types. These ones are built

 * using the predefined types in Gmm++
 */
typedef getfem::modeling_standard_sparse_vector sparse_vector;
typedef getfem::modeling_standard_sparse_matrix sparse_matrix;
typedef getfem::modeling_standard_plain_vector  plain_vector;

/**************************************************************************/
/*  Exact solution.                                                       */
/**************************************************************************/

#define VALIDATE_XFEM

#ifdef VALIDATE_XFEM

/* returns sin(theta/2) where theta is the angle
   of 0-(x,y) with the axis Ox */
scalar_type sint2(scalar_type x, scalar_type y) {
  scalar_type r = sqrt(x*x+y*y);
  if (r == 0) return 0;
  else return (y<0 ? -1:1) * sqrt(gmm::abs(r-x)/(2*r));
  // sometimes (gcc3.3.2 -O3), r-x < 0 ....
}
scalar_type cost2(scalar_type x, scalar_type y) {
  scalar_type r = sqrt(x*x+y*y);
  if (r == 0) return 0;
  else return sqrt(gmm::abs(r+x)/(2*r));
}
/* analytical solution for a semi-infinite crack [-inf,a] in an
   infinite plane submitted to +sigma above the crack
   and -sigma under the crack. (The crack is directed along the x axis).

   nu and E are the poisson ratio and young modulus

   solution taken from "an extended finite elt method with high order
   elts for curved cracks", Stazi, Budyn,Chessa, Belytschko
*/

void elasticite2lame(const scalar_type young_modulus,
                     const scalar_type poisson_ratio,
                     scalar_type& lambda, scalar_type& mu) {
  mu = young_modulus/(2*(1+poisson_ratio));
  lambda = 2*mu*poisson_ratio/(1-poisson_ratio);
}

void sol_ref_infinite_plane(scalar_type nu, scalar_type E, scalar_type sigma,
                            scalar_type a, scalar_type xx, scalar_type y,
                            base_small_vector& U, int mode,
                            base_matrix *pgrad) {
  scalar_type x  = xx-a; /* the eq are given relatively to the crack tip */
  //scalar_type KI = sigma*sqrt(M_PI*a);
  scalar_type r = std::max(sqrt(x*x+y*y),1e-16);
  scalar_type sqrtr = sqrt(r), sqrtr3 = sqrtr*sqrtr*sqrtr;
  scalar_type cost = x/r, sint = y/r;
  scalar_type theta = atan2(y,x);
  scalar_type s2 = sin(theta/2); //sint2(x,y);
  scalar_type c2 = cos(theta/2); //cost2(x,y);
  // scalar_type c3 = cos(3*theta/2); //4*c2*c2*c2-3*c2; /* cos(3*theta/2) */
  // scalar_type s3 = sin(3*theta/2); //4*s2*c2*c2-s2;  /* sin(3*theta/2) */

  scalar_type lambda, mu;
  elasticite2lame(E,nu,lambda,mu);

  U.resize(2);
  if (pgrad) (*pgrad).resize(2,2);
  scalar_type C= 1./E * (mode == 1 ? 1. : (1+nu));
  if (mode == 1) {
    scalar_type A=2+2*mu/(lambda+2*mu);
    scalar_type B=-2*(lambda+mu)/(lambda+2*mu);
    U[0] = sqrtr/sqrt(2*M_PI) * C * c2 * (A + B*cost);
    U[1] = sqrtr/sqrt(2*M_PI) * C * s2 * (A + B*cost);
    if (pgrad) {
      (*pgrad)(0,0) = C/(2.*sqrt(2*M_PI)*sqrtr)
        * (cost*c2*A-cost*cost*c2*B+sint*s2*A+sint*s2*B*cost+2*c2*B);
      (*pgrad)(1,0) = -C/(2*sqrt(2*M_PI)*sqrtr)
        * (-sint*c2*A+sint*c2*B*cost+cost*s2*A+cost*cost*s2*B);
      (*pgrad)(0,1) = C/(2.*sqrt(2*M_PI)*sqrtr)
        * (cost*s2*A-cost*cost*s2*B-sint*c2*A-sint*c2*B*cost+2*s2*B);
      (*pgrad)(1,1) = C/(2.*sqrt(2*M_PI)*sqrtr)
        * (sint*s2*A-sint*s2*B*cost+cost*c2*A+cost*cost*c2*B);
    }
  } else if (mode == 2) {
    scalar_type C1 = (lambda+3*mu)/(lambda+mu);
    U[0] = sqrtr/sqrt(2*M_PI) * C * s2 * (C1 + 2 + cost);
    U[1] = sqrtr/sqrt(2*M_PI) * C * c2 * (C1 - 2 + cost) * (-1.);
    if (pgrad) {
      (*pgrad)(0,0) = C/(2.*sqrt(2*M_PI)*sqrtr)
        * (cost*s2*C1+2*cost*s2-cost*cost*s2-sint*c2*C1
           -2*sint*c2-sint*cost*c2+2*s2);
      (*pgrad)(1,0) = C/(2.*sqrt(2*M_PI)*sqrtr)
        * (sint*s2*C1+2*sint*s2-sint*s2*cost+cost*c2*C1
           +2*cost*c2+cost*cost*c2);
      (*pgrad)(0,1) = -C/(2.*sqrt(2*M_PI)*sqrtr)
        * (cost*c2*C1-2*cost*c2-cost*cost*c2+sint*s2*C1
           -2*sint*s2+sint*s2*cost+2*c2);
      (*pgrad)(1,1) =  C/(2.*sqrt(2*M_PI)*sqrtr)
        * (-sint*c2*C1+2*sint*c2+sint*cost*c2+cost*s2*C1
           -2*cost*s2+cost*cost*s2);
    }
  } else if (mode == 100) {
    U[0] = - sqrtr3 * (c2 + 4./3 *(7*mu+3*lambda)/(lambda+mu)*c2*s2*s2
                       -1./3*(7*mu+3*lambda)/(lambda+mu)*c2);
    U[1] = - sqrtr3 * (s2+4./3*(lambda+5*mu)/(lambda+mu)*s2*s2*s2
                       -(lambda+5*mu)/(lambda+mu)*s2);
    if (pgrad) {
      (*pgrad)(0,0) = 2*sqrtr*(-6*cost*c2*mu+7*cost*c2*c2*c2*mu
                               -3*cost*c2*lambda+3*cost*c2*c2*c2*lambda
                               -2*sint*s2*mu
                               +7*sint*s2*c2*c2*mu-sint*s2*lambda
                               +3*sint*s2*c2*c2*lambda)/(lambda+mu);
      (*pgrad)(1,0) = -2*sqrtr*(6*sint*c2*mu-7*sint*c2*c2*c2*mu
                                +3*sint*c2*lambda-3*sint*c2*c2*c2*lambda
                                -2*cost*s2*mu
                                +7*cost*s2*c2*c2*mu-cost*s2*lambda
                                +3*cost*s2*c2*c2*lambda)/(lambda+mu);
      (*pgrad)(0,1) = 2*sqrtr*(-2*cost*s2*mu-cost*s2*lambda
                               +cost*s2*c2*c2*lambda+5*cost*s2*c2*c2*mu
                               +4*sint*c2*mu
                               +sint*c2*lambda-sint*c2*c2*c2*lambda
                               -5*sint*c2*c2*c2*mu)/(lambda+mu);
      (*pgrad)(1,1) = 2*sqrtr*(-2*sint*s2*mu-sint*s2*lambda
                               +sint*s2*c2*c2*lambda+5*sint*s2*c2*c2*mu
                               -4*cost*c2*mu
                               -cost*c2*lambda+cost*c2*c2*c2*lambda
                               +5*cost*c2*c2*c2*mu)/(lambda+mu);
    }
  } else if (mode == 101) {
    U[0] = -4*sqrtr3*s2*(-lambda-2*mu+7*lambda*c2*c2
                         +11*mu*c2*c2)/(3*lambda-mu);
    U[1] = -4*sqrtr3*c2*(-3*lambda+3*lambda*c2*c2-mu*c2*c2)/(3*lambda-mu);
    if (pgrad) {
      (*pgrad)(0,0) = -6*sqrtr*(-cost*s2*lambda-2*cost*s2*mu
                                +7*cost*s2*lambda*c2*c2
                                +11*cost*s2*mu*c2*c2+5*sint*c2*lambda
                                +8*sint*c2*mu-7*sint*c2*c2*c2*lambda
                                -11*sint*c2*c2*c2*mu)/(3*lambda-mu);
      (*pgrad)(1,0) = -6*sqrtr*(-sint*s2*lambda-2*sint*s2*mu
                                +7*sint*s2*lambda*c2*c2
                                +11*sint*s2*mu*c2*c2-5*cost*c2*lambda
                                -8*cost*c2*mu+7*cost*c2*c2*c2*lambda
                                +11*cost*c2*c2*c2*mu)/(3*lambda-mu);
      (*pgrad)(0,1) = -6*sqrtr*(-3*cost*c2*lambda+3*cost*c2*c2*c2*lambda
                                -cost*c2*c2*c2*mu-sint*s2*lambda
                                +3*sint*s2*lambda*c2*c2
                                -sint*s2*mu*c2*c2)/(3*lambda-mu);
      (*pgrad)(1,1) = 6*sqrtr*(3*sint*c2*lambda
                               -3*sint*c2*c2*c2*lambda+sint*c2*c2*c2*mu
                               -cost*s2*lambda+3*cost*s2*lambda*c2*c2
                               -cost*s2*mu*c2*c2)/(3*lambda-mu);
    }

  } else if (mode == 10166666) {

    U[0] = 4*sqrtr3*s2*(-lambda+lambda*c2*c2-3*mu*c2*c2)/(lambda-3*mu);
    U[1] = 4*sqrtr3*c2*(-3*lambda-6*mu+5*lambda*c2*c2+9*mu*c2*c2)/(lambda-3*mu);
    if (pgrad) {
      (*pgrad)(0,0) = 6*sqrtr*(-cost*s2*lambda+cost*s2*lambda*c2*c2-
                               3*cost*s2*mu*c2*c2-2*sint*c2*mu+sint*c2*lambda-
                               sint*c2*c2*c2*lambda
                               +3*sint*c2*c2*c2*mu)/(lambda-3*mu);
      (*pgrad)(1,0) = 6*sqrtr*(-sint*s2*lambda+sint*s2*lambda*c2*c2-
                               3*sint*s2*mu*c2*c2+2*cost*c2*mu-cost*c2*lambda+
                               cost*c2*c2*c2*lambda
                               -3*cost*c2*c2*c2*mu)/(lambda-3*mu);
      (*pgrad)(0,1) = 6*sqrtr*(-3*cost*c2*lambda-6*cost*c2*mu
                               +5*cost*c2*c2*c2*lambda+
                               9*cost*c2*c2*c2*mu-sint*s2*lambda-2*sint*s2*mu+
                               5*sint*s2*lambda*c2*c2
                               +9*sint*s2*mu*c2*c2)/(lambda-3*mu);
      (*pgrad)(1,1) = -6*sqrtr*(3*sint*c2*lambda+6*sint*c2*mu
                                -5*sint*c2*c2*c2*lambda-
                                9*sint*c2*c2*c2*mu-cost*s2*lambda-2*cost*s2*mu+
                                5*cost*s2*lambda*c2*c2
                                +9*cost*s2*mu*c2*c2)/(lambda-3*mu);
    }
  } else assert(0);
  if (std::isnan(U[0]))
    cerr << "raaah not a number ... nu=" << nu << ", E=" << E << ", sig="
         << sigma << ", a=" << a << ", xx=" << xx << ", y=" << y << ", r="
         << r << ", sqrtr=" << sqrtr << ", cost=" << cost << ", U=" << U[0]
         << "," << U[1] << endl;
  assert(!std::isnan(U[0]));
  assert(!std::isnan(U[1]));
}

struct exact_solution {
  getfem::mesh_fem_global_function mf;
  getfem::base_vector U;

  exact_solution(getfem::mesh &me) : mf(me) {}

  void init(int mode, scalar_type lambda, scalar_type mu,
            getfem::level_set &ls) {
    std::vector<getfem::pglobal_function> cfunc(4);

 for (unsigned i = 0; i < 4; ++i) {
   /* use the singularity */
   getfem::pxy_function
     s = std::make_shared<getfem::crack_singular_xy_function>(i);
    cfunc[i] = getfem::global_function_on_level_set(ls, s);
 }

    mf.set_functions(cfunc);

    mf.set_qdim(1);


    U.resize(8); assert(mf.nb_dof() == 4);
    getfem::base_vector::iterator it = U.begin();
    scalar_type coeff=0.;
    switch(mode) {
      case 1: {
        scalar_type A=2+2*mu/(lambda+2*mu), B=-2*(lambda+mu)/(lambda+2*mu);
        /* "colonne" 1: ux, colonne 2: uy */
        *it++ = 0;       *it++ = A-B; /* sin(theta/2) */
        *it++ = A+B;     *it++ = 0;   /* cos(theta/2) */
        *it++ = -B;      *it++ = 0;   /* sin(theta/2)*sin(theta) */
        *it++ = 0;       *it++ = B;   /* cos(theta/2)*cos(theta) */
        coeff = 1/sqrt(2*M_PI);
      } break;
      case 2: {
        scalar_type C1 = (lambda+3*mu)/(lambda+mu);
        *it++ = C1+2-1;   *it++ = 0;
        *it++ = 0;      *it++ = -(C1-2+1);
        *it++ = 0;      *it++ = 1;
        *it++ = 1;      *it++ = 0;
        coeff = 2*(mu+lambda)/(lambda+2*mu)/sqrt(2*M_PI);
      } break;
      default:
        assert(0);
        break;
    }
    gmm::scale(U, coeff);
  }
};

base_small_vector sol_f(const base_node &x) {
  int N = x.size();
  base_small_vector res(N);
  return res;
}

#else

base_small_vector sol_f(const base_node &x) {
  int N = x.size();
  base_small_vector res(N); res[N-1] = x[N-1];
  return res;
}

#endif


/**************************************************************************/
/*  Structure for the crack problem.                                      */
/**************************************************************************/

struct crack_problem {

  enum { DIRICHLET_BOUNDARY_NUM = 0, NEUMANN_BOUNDARY_NUM_down = 1, NEUMANN_BOUNDARY_NUM_up=2, NEUMANN_BOUNDARY_NUM_right=3};
  getfem::mesh mesh;  /* the mesh */
  getfem::mesh_level_set mls;       /* the integration methods.              */
  getfem::mesh_im_level_set mim;    /* the integration methods.              */
  getfem::mesh_fem mf_pre_u;
  getfem::mesh_fem mf_mult;
  getfem::mesh_fem_level_set mfls_u;
  getfem::mesh_fem_sum mf_u_sum;

  getfem::mesh_fem& mf_u() { return mf_u_sum; }

  scalar_type lambda, mu;    /* Lame coefficients.                */
  getfem::mesh_fem mf_rhs;   /* mesh_fem for the right hand side (f(x),..)   */

#ifdef VALIDATE_XFEM
  exact_solution exact_sol;
#endif


  double lx,ly;             /* size of the mesh */
  int bimaterial;           /* For bimaterial interface fracture */
  bool all_dirichlet;
  double F11,F12,F21,F22,F31,F32,F41,F42;       /* NEUMANN forces */
  double neumann_value;   /* NEUMANN force value */
  int mode;
  double lambda_up, lambda_down, mu_up, mu_down;  /*Lame coeff for bimaterial case*/
  getfem::level_set ls;      /* The two level sets defining the crack.       */

  base_small_vector translation;

  scalar_type residual;       /* max residual for the iterative solvers        */
  size_type conv_max;

  std::string datafilename;
  bgeot::md_param PARAM;

  bool adapted_refine, solve(plain_vector &U);

  void init(void);
  crack_problem(void) : mls(mesh), mim(mls), mf_pre_u(mesh), mf_mult(mesh),
                        mfls_u(mls, mf_pre_u),

                        mf_u_sum(mesh), mf_rhs(mesh),
#ifdef VALIDATE_XFEM
                        exact_sol(mesh),
#endif
                        ls(mesh, 1, true) {}

};

/* Read parameters from the .param file, build the mesh, set finite element
 * and integration methods and selects the boundaries.
 */
void crack_problem::init(void) {
  std::string MESH_TYPE = PARAM.string_value("MESH_TYPE","Mesh type ");
  std::string FEM_TYPE  = PARAM.string_value("FEM_TYPE","FEM name");

  std::string INTEGRATION = PARAM.string_value("INTEGRATION",
                                               "Name of integration method");
  std::string SIMPLEX_INTEGRATION = PARAM.string_value("SIMPLEX_INTEGRATION",
                                         "Name of simplex integration method");
  std::string SINGULAR_INTEGRATION = PARAM.string_value("SINGULAR_INTEGRATION");


  cout << "MESH_TYPE=" << MESH_TYPE << "\n";
  cout << "FEM_TYPE="  << FEM_TYPE << "\n";
  cout << "INTEGRATION=" << INTEGRATION << "\n";


  /* First step : build the mesh */
  bgeot::pgeometric_trans pgt =
    bgeot::geometric_trans_descriptor(MESH_TYPE);
  size_type N = pgt->dim();
  std::vector<size_type> nsubdiv(N);
  std::fill(nsubdiv.begin(),nsubdiv.end(),
            PARAM.int_value("NX", "Nomber of space steps "));
  getfem::regular_unit_mesh(mesh, nsubdiv, pgt,
                            PARAM.int_value("MESH_NOISED") != 0);


  lx = PARAM.real_value("LX","length x'ox");
  ly = PARAM.real_value("LY","length y'oy");

  bgeot::base_matrix M(2,2);
  M(0,0) = lx;
  M(1,1) = ly;
  mesh.transformation(M);

  base_small_vector tt(N); tt[0] = tt[1] = -(lx/2.);
  mesh.translation(tt);

  conv_max = PARAM.int_value("CONV_MAX","Maximal number of convexes in the mesh");
  adapted_refine = PARAM.int_value("ADAPTED_REFINE","Adapted Refinement");

  scalar_type refinement_radius;
  refinement_radius = PARAM.real_value("REFINEMENT_RADIUS","Refinement Radius");
  size_type refinement_process;
  refinement_process = PARAM.int_value("REFINEMENT_PROCESS","Refinement process");
  dal::bit_vector conv_to_refine;
  size_type ref = 1;
  if (refinement_radius > 0){
    while(ref <= refinement_process){
      conv_to_refine.clear();
      for(dal::bv_visitor i(mesh.convex_index()); !i.finished(); ++i){
      for(size_type j=0; j < 3; ++j)
        if(fabs(mesh.points()[mesh.ind_points_of_convex(i)[j]][0])<refinement_radius
           && fabs(mesh.points()[mesh.ind_points_of_convex(i)[j]][1])<refinement_radius){
          conv_to_refine.add(i);
        }
      }
      mesh.Bank_refine(conv_to_refine);

      ref = ref + 1;
      refinement_radius = refinement_radius/2.;
      if(refinement_radius > 1e-16 )
        cout<<"refining process step " << ref << "... refining "<< conv_to_refine.size() <<" convexes..." << endl ;

    }
  cout<<"refining process complete." << endl ;
  }
  datafilename = PARAM.string_value("ROOTFILENAME","Base name of data files.");
  residual = PARAM.real_value("RESIDUAL");
  if (residual == 0.) residual = 1e-10;

  bimaterial = int(PARAM.int_value("BIMATERIAL", "Bimaterial interface crack"));
  all_dirichlet = PARAM.int_value("all_dirichlet", "Dirichlet condition");
  mode = int(PARAM.int_value("mode","mode"));

  //F11 = PARAM.real_value("F11","F11");
  //F12 = PARAM.real_value("F12","F12");
  //F21 = PARAM.real_value("F21","F21");
  //F22 = PARAM.real_value("F22","F22");
  //F31 = PARAM.real_value("F31","F31");
  //F32 = PARAM.real_value("F32","F32");
  //F41 = PARAM.real_value("F41","F41");
  //F42 = PARAM.real_value("F42","F42");

  neumann_value = PARAM.real_value("NEUMANN_VALUE","neumann_value");

  if (bimaterial == 1){
    mu = PARAM.real_value("MU", "Lame coefficient mu");
    lambda_up = PARAM.real_value("LAMBDA_UP", "Lame Coef");
    lambda_down = PARAM.real_value("LAMBDA_DOWN", "Lame Coef");
    lambda = PARAM.real_value("LAMBDA", "Lame coefficient lambda");
    mu_up = PARAM.real_value("MU_UP", "Lame Coef");
    mu_down = PARAM.real_value("MU_DOWN", "Lame Coef");

  }
  else{

    mu = PARAM.real_value("MU", "Lame coefficient mu");
    lambda = PARAM.real_value("LAMBDA", "Lame coefficient lambda");
  }


  mf_u().set_qdim(dim_type(N));


  /* set the finite element on the mf_u */
  getfem::pfem pf_u =
    getfem::fem_descriptor(FEM_TYPE);


  getfem::pintegration_method ppi =
    getfem::int_method_descriptor(INTEGRATION);
  getfem::pintegration_method simp_ppi =
    getfem::int_method_descriptor(SIMPLEX_INTEGRATION);
  getfem::pintegration_method sing_ppi = (SINGULAR_INTEGRATION.size() ? getfem::int_method_descriptor(SINGULAR_INTEGRATION) : 0);

  mim.set_integration_method(mesh.convex_index(), ppi);
  mls.add_level_set(ls);


  mim.set_simplex_im(simp_ppi, sing_ppi);
  mf_pre_u.set_finite_element(mesh.convex_index(), pf_u);
  mf_mult.set_finite_element(mesh.convex_index(), pf_u);
  mf_mult.set_qdim(dim_type(N));


  /* set the finite element on mf_rhs (same as mf_u is DATA_FEM_TYPE is
     not used in the .param file */
  std::string data_fem_name = PARAM.string_value("DATA_FEM_TYPE");
  if (data_fem_name.size() == 0) {
    GMM_ASSERT1(pf_u->is_lagrange(), "You are using a non-lagrange FEM. "
                << "In that case you need to set "
                << "DATA_FEM_TYPE in the .param file");
    mf_rhs.set_finite_element(mesh.convex_index(), pf_u);
  } else {
    mf_rhs.set_finite_element(mesh.convex_index(),
                              getfem::fem_descriptor(data_fem_name));
  }

  /* set boundary conditions
   * (Neuman on the upper face, Dirichlet elsewhere) */
  cout << "Selecting Neumann and Dirichlet boundaries\n";
  getfem::mesh_region border_faces;
  getfem::outer_faces_of_mesh(mesh, border_faces);
  for (getfem::mr_visitor i(border_faces); !i.finished(); ++i) {

    base_node un = mesh.normal_of_face_of_convex(i.cv(), i.f());
    un /= gmm::vect_norm2(un);
    if(all_dirichlet)
      mesh.region(DIRICHLET_BOUNDARY_NUM).add(i.cv(), i.f());
    else {
      if (un[0]  > 1.0E-7 ) { // new Neumann face
        mesh.region(DIRICHLET_BOUNDARY_NUM).add(i.cv(), i.f());
      } else {
        if (un[1]  > 1.0E-7 ) {
          //cout << "normal = " << un << endl;
          mesh.region(NEUMANN_BOUNDARY_NUM_up).add(i.cv(), i.f());
        }
        else {
          if (un[1]  < -1.0E-7 ) {
            //cout << "normal = " << un << endl;
            mesh.region(NEUMANN_BOUNDARY_NUM_down).add(i.cv(), i.f());
          }
          else {

            if (un[0]  < -1.0E-7 ) {

              if(mesh.points_of_convex(i.cv())[mesh.structure_of_convex(i.cv())->ind_points_of_face(i.f())[0]][1] > 1.0E-16 ||  mesh.points_of_convex(i.cv())[mesh.structure_of_convex(i.cv())->ind_points_of_face(i.f())[1]][1] > 1.0E-16) {

                // cout << "normal = " << un << endl;
                mesh.region(NEUMANN_BOUNDARY_NUM_right).add(i.cv(), i.f());
              }
              else
                mesh.region(NEUMANN_BOUNDARY_NUM_right+1).add(i.cv(), i.f());
            }
          }
        }
      }
    }
  }
#ifdef VALIDATE_XFEM
  exact_sol.init(1, lambda, mu, ls);
#endif
}


base_small_vector ls_function(const base_node P, int num = 0) {

  scalar_type x = P[0], y = P[1];
  base_small_vector res(2);
  switch (num) {
    case 0: {
      res[0] =  y;
      res[1] =  x;
    } break;
    case 1: {
      res[0] = gmm::vect_dist2(P, base_node(0.5, 0.)) - .25;
      res[1] = gmm::vect_dist2(P, base_node(0.25, 0.0)) - 0.27;
    } break;
    case 2: {
      res[0] = x - 0.25;
      res[1] = gmm::vect_dist2(P, base_node(0.25, 0.0)) - 0.35;
    } break;
    default: assert(0);
  }
  return res;
}

bool crack_problem::solve(plain_vector &U) {
  size_type N = mesh.dim();


  // Linearized elasticity brick.
  dal::bit_vector conv_to_refine;
  bool iteration(false);

  switch (mode) {
  case 1:
  case 2:{
    if (mode == 1){
      cout << "Mode I problem..." << endl;
      F11 = 0; F12 = neumann_value; F21 = 0; F22 = 0; F31 = 0; F32 = 0; F41 = 0; F42 = -neumann_value;
    } else
      if(mode == 2){
        cout << "Mode II problem..." << endl;
        F11 = 0; F12 = 0; F21 = neumann_value; F22 = 0; F31 = -neumann_value; F32 = 0; F41 = 0; F42 = 0;
      }

    do {
      cout << "Number of convexes : "<<  mesh.convex_index().size() <<endl;
      size_type nb_dof_rhs = mf_rhs.nb_dof();
      ls.reinit();
      cout << "ls.get_mesh_fem().nb_dof() = " << ls.get_mesh_fem().nb_dof() << "\n";
      for (size_type d = 0; d < ls.get_mesh_fem().nb_dof(); ++d) {
        ls.values(0)[d] = ls_function(ls.get_mesh_fem().point_of_basic_dof(d), 0)[0];
        ls.values(1)[d] = ls_function(ls.get_mesh_fem().point_of_basic_dof(d), 0)[1];
      }
      ls.touch();
      mls.adapt();
      mim.adapt();
      mfls_u.adapt();

      mf_u_sum.set_mesh_fems(mfls_u);

      U.resize(mf_u().nb_dof());

      conv_to_refine.clear();

      getfem::model model;

      // Main unknown of the problem.
      model.add_fem_variable("u", mf_u());
      plain_vector lambda_(mf_rhs.nb_dof(), lambda);
      model.add_initialized_fem_data("lambda", mf_rhs, lambda_);
      plain_vector mu_(mf_rhs.nb_dof(), mu);
      model.add_initialized_fem_data("mu", mf_rhs, mu_);
      getfem::add_isotropic_linearized_elasticity_brick
        (model, mim, "u", "lambda", "mu");


      if(bimaterial == 1){
        GMM_ASSERT1(!mf_rhs.is_reduced(), "To be adapted");
        cout<<"______________________________________________________________________________"<<endl;
        cout<<"CASE OF BIMATERIAL CRACK  with lambda_up = "<<lambda_up<<" and lambda_down = "<<lambda_down<<endl;
        cout<<"______________________________________________________________________________"<<endl;
        plain_vector bi_lambda(mf_rhs.nb_dof());
        plain_vector bi_mu(mf_rhs.nb_dof());

        for (size_type ite = 0; ite < mf_rhs.nb_dof(); ite++) {
          if (mf_rhs.point_of_basic_dof(ite)[1] > 0){
            bi_lambda[ite] = lambda_up;
            bi_mu[ite] = mu_up;
          }
          else{
            bi_lambda[ite] = lambda_down;
            bi_mu[ite] = mu_down;
          }
        }

        gmm::copy(bi_lambda, model.set_real_variable("lambda"));
        gmm::copy(bi_mu, model.set_real_variable("mu"));
      }


      // Defining the volumic source term.
      plain_vector F(nb_dof_rhs * N);
      getfem::interpolation_function(mf_rhs, F, sol_f);
      model.add_initialized_fem_data("VolumicData", mf_rhs, F);
      getfem::add_source_term_brick(model, mim, "u", "VolumicData");


      // Defining the Neumann condition right hand side.

      // Neumann condition brick.

      if (!all_dirichlet) {

        gmm::clear(F);
        for(size_type i = 0; i<F.size(); i=i+2) {F[i] = F41; F[i+1] = F42;}
        model.add_initialized_fem_data("NeumannData_down", mf_rhs, F);
        getfem::add_source_term_brick
          (model, mim, "u", "NeumannData_down", NEUMANN_BOUNDARY_NUM_down);

        gmm::clear(F);
        for(size_type i = 0; i<F.size(); i=i+2)  {F[i] = F21; F[i+1] = F22;}
        model.add_initialized_fem_data("NeumannData_right", mf_rhs, F);
        getfem::add_source_term_brick
          (model, mim, "u", "NeumannData_right", NEUMANN_BOUNDARY_NUM_right);

        gmm::clear(F);
        for(size_type i = 0; i<F.size(); i=i+2) {F[i] = F31; F[i+1] = F32;}
        model.add_initialized_fem_data("NeumannData_right_down", mf_rhs, F);
        getfem::add_source_term_brick
          (model, mim, "u", "NeumannData_right_down",
           NEUMANN_BOUNDARY_NUM_right+1);

        gmm::clear(F);
        for(size_type i = 0; i<F.size(); i=i+2) {F[i] = F11; F[i+1] = F12;}
        model.add_initialized_fem_data("NeumannData_up", mf_rhs, F);
        getfem::add_source_term_brick
          (model, mim, "u", "NeumannData_up", NEUMANN_BOUNDARY_NUM_up);
      }


      // Dirichlet condition brick.
      if (all_dirichlet) {
#ifdef VALIDATE_XFEM
        model.add_initialized_fem_data("DirichletData", exact_sol.mf,
                                       exact_sol.U);
        getfem::add_Dirichlet_condition_with_multipliers
          (model, mim, "u", mf_mult, DIRICHLET_BOUNDARY_NUM, "DirichletData");
#else
        getfem::add_Dirichlet_condition_with_multipliers
          (model, mim, "u", mf_mult, DIRICHLET_BOUNDARY_NUM);
#endif
      } else {
        getfem::add_Dirichlet_condition_with_multipliers
          (model, mim, "u", mf_mult, DIRICHLET_BOUNDARY_NUM);
      }


      // Generic solve.
      cout << "Total number of variables : " << model.nb_dof() << endl;
      gmm::iteration iter(residual, 1, 40000);
      getfem::standard_solve(model, iter);

      // Solution extraction
      gmm::resize(U, mf_u().nb_dof());
      gmm::copy(model.real_variable("u"), U);
      iteration = iter.converged();

      // Adapted Refinement (suivant une erreur a posteriori)
      if (adapted_refine) {
        if (mesh.convex_index().size() < conv_max){
          plain_vector ERR(mesh.convex_index().last_true()+1);
          getfem::error_estimate(mim, mf_u(), U, ERR);

          cout << "max = " << gmm::vect_norminf(ERR) << endl;
          scalar_type threshold = 0.01, min_ = 1e18;
          conv_to_refine.clear();
          for (dal::bv_visitor i(mesh.convex_index()); !i.finished(); ++i) {
            if (ERR[i] > threshold && mesh.points()[mesh.ind_points_of_convex(i)[0]][0] >= -0.1)
              conv_to_refine.add(i);
            min_ = std::min(min_, ERR[i]);
          }
          cout << "min = " << min_ << endl;
      cout << "Refining " <<  conv_to_refine.card() << " convexes..."<< endl;
      mesh.Bank_refine(conv_to_refine);
        }
        else
          break;
      }
    } while(adapted_refine && conv_to_refine.size() > 0);
    mesh.write_to_file(datafilename + ".meshh");
    cout << "Refining process complete. The mesh contains now " <<  mesh.convex_index().size() << " convexes "<<endl;

    GMM_ASSERT1(!mf_u().is_reduced(), "To be adapted");

    dal::bit_vector blocked_dof = mf_u().basic_dof_on_region(5);
    getfem::mesh_fem mf_printed(mesh, dim_type(N));
    std::string FEM_DISC = PARAM.string_value("FEM_DISC","fem disc ");
    mf_printed.set_finite_element(mesh.convex_index(),
                                  getfem::fem_descriptor(FEM_DISC));

    plain_vector W(mf_printed.nb_dof());
    getfem::interpolation(mf_u(), mf_printed, U, W);

    std::ostringstream oss;
    oss << mode;
    std::string mode_string = oss.str();

    mf_printed.write_to_file(datafilename + mode_string +  ".meshfem", true);
    gmm::vecsave(datafilename + mode_string + ".U", W);

  }break;

  case 12: {
    int mode_counter = 1;
    plain_vector W12;
    W12.clear();
    getfem::mesh_fem mf_printed(mesh, dim_type(N));
    dal::bit_vector blocked_dof;

    std::string FEM_DISC = PARAM.string_value("FEM_DISC","fem disc ");

    do{
      cout << "Computing mode " << mode_counter << " solution..." <<endl;

      if (mode_counter == 1){
        F11 = 0; F12 = neumann_value; F21 = 0; F22 = 0; F31 = 0; F32 = 0; F41 = 0; F42 = -neumann_value;
        //F11 = 0; F12 = 0; F21 = neumann_value; F22 = 0; F31 = -neumann_value; F32 = 0; F41 = 0; F42 = 0;
      } else

        if(mode_counter == 2){
          F11 = 0; F12 = 0; F21 = neumann_value; F22 = 0; F31 = -neumann_value; F32 = 0; F41 = 0; F42 = 0;
          //F11 = 0; F12 = neumann_value; F21 = 0; F22 = 0; F31 = 0; F32 = 0; F41 = 0; F42 = -neumann_value;
        }

      do {
        cout << "Number of convexes : "<<  mesh.convex_index().size() <<endl;
        size_type nb_dof_rhs = mf_rhs.nb_dof();

        if (mode_counter == 1) {
          ls.reinit();
          cout << "ls.get_mesh_fem().nb_dof() = " << ls.get_mesh_fem().nb_dof() << "\n";
          for (size_type d = 0; d < ls.get_mesh_fem().nb_dof(); ++d) {
            ls.values(0)[d] = ls_function(ls.get_mesh_fem().point_of_basic_dof(d), 0)[0];
            ls.values(1)[d] = ls_function(ls.get_mesh_fem().point_of_basic_dof(d), 0)[1];
          }
          ls.touch();
          mls.adapt();
          mim.adapt();
          mfls_u.adapt();
          mf_u_sum.set_mesh_fems(mfls_u);
          U.resize(mf_u().nb_dof());
        }

        conv_to_refine.clear();

        getfem::model model;

        // Main unknown of the problem.
        model.add_fem_variable("u", mf_u());
        plain_vector lambda_(mf_rhs.nb_dof(), lambda);
        model.add_initialized_fem_data("lambda", mf_rhs, lambda_);
        plain_vector mu_(mf_rhs.nb_dof(), mu);
        model.add_initialized_fem_data("mu", mf_rhs, mu_);
        getfem::add_isotropic_linearized_elasticity_brick
          (model, mim, "u", "lambda", "mu");


        if(bimaterial == 1){
          GMM_ASSERT1(!mf_rhs.is_reduced(), "To be adapted");
          cout<<"______________________________________________________________________________"<<endl;
          cout<<"CASE OF BIMATERIAL CRACK  with lambda_up = "<<lambda_up<<" and lambda_down = "<<lambda_down<<endl;
          cout<<"______________________________________________________________________________"<<endl;
          plain_vector bi_lambda(mf_rhs.nb_dof());
          plain_vector bi_mu(mf_rhs.nb_dof());

          for (size_type ite = 0; ite < mf_rhs.nb_dof(); ite++) {
            if (mf_rhs.point_of_basic_dof(ite)[1] > 0){
              bi_lambda[ite] = lambda_up;
              bi_mu[ite] = mu_up;
            }
            else{
              bi_lambda[ite] = lambda_down;
              bi_mu[ite] = mu_down;
            }
          }

          gmm::copy(bi_lambda, model.set_real_variable("lambda"));
          gmm::copy(bi_mu, model.set_real_variable("mu"));
        }


        // Defining the volumic source term.

        // Volumic source term brick.
        plain_vector F(nb_dof_rhs * N);
        getfem::interpolation_function(mf_rhs, F, sol_f);
        model.add_initialized_fem_data("VolumicData", mf_rhs, F);
        getfem::add_source_term_brick(model, mim, "u", "VolumicData");

        // Defining the Neumann condition right hand side.

        // Neumann condition brick.

        if (!all_dirichlet) {

          gmm::clear(F);
          for(size_type i = 0; i<F.size(); i=i+2) {F[i] = F41; F[i+1] = F42;}
          model.add_initialized_fem_data("NeumannData_down", mf_rhs, F);
          getfem::add_source_term_brick
            (model, mim, "u", "NeumannData_down", NEUMANN_BOUNDARY_NUM_down);

          gmm::clear(F);
          for(size_type i = 0; i<F.size(); i=i+2)  {F[i] = F21; F[i+1] = F22;}
          model.add_initialized_fem_data("NeumannData_right", mf_rhs, F);
          getfem::add_source_term_brick
            (model, mim, "u", "NeumannData_right", NEUMANN_BOUNDARY_NUM_right);

          gmm::clear(F);
          for(size_type i = 0; i<F.size(); i=i+2) {F[i] = F31; F[i+1] = F32;}
          model.add_initialized_fem_data("NeumannData_right_down", mf_rhs, F);
          getfem::add_source_term_brick
            (model, mim, "u", "NeumannData_right_down",
             NEUMANN_BOUNDARY_NUM_right+1);

          gmm::clear(F);
          for(size_type i = 0; i<F.size(); i=i+2) {F[i] = F11; F[i+1] = F12;}
          model.add_initialized_fem_data("NeumannData_up", mf_rhs, F);
          getfem::add_source_term_brick
            (model, mim, "u", "NeumannData_up", NEUMANN_BOUNDARY_NUM_up);
        }

        // Dirichlet condition brick.
        if (all_dirichlet) {
#ifdef VALIDATE_XFEM
          model.add_initialized_fem_data("DirichletData", exact_sol.mf,
                                         exact_sol.U);
          getfem::add_Dirichlet_condition_with_multipliers
            (model, mim, "u", mf_mult, DIRICHLET_BOUNDARY_NUM,"DirichletData");
#else
          getfem::add_Dirichlet_condition_with_multipliers
            (model, mim, "u", mf_mult, DIRICHLET_BOUNDARY_NUM);
#endif
        } else {
          getfem::add_Dirichlet_condition_with_multipliers
            (model, mim, "u", mf_mult, DIRICHLET_BOUNDARY_NUM);
        }

        // Generic solve.
        cout << "Total number of variables : " << model.nb_dof() << endl;
        gmm::iteration iter(residual, 1, 40000);
        getfem::standard_solve(model, iter);

        // Solution extraction
        gmm::resize(U, mf_u().nb_dof());
        gmm::copy(model.real_variable("u"), U);
        iteration = iter.converged();

        // Adapted Refinement (suivant une erreur a posteriori)
        if (adapted_refine && mode_counter == 1) {
          if (mesh.convex_index().size() < conv_max){
            plain_vector ERR(mesh.convex_index().last_true()+1);
            getfem::error_estimate(mim, mf_u(), U, ERR);

            cout << "max = " << gmm::vect_norminf(ERR) << endl;
            scalar_type threshold = 0.01, min_ = 1e18;
            conv_to_refine.clear();
            for (dal::bv_visitor i(mesh.convex_index()); !i.finished(); ++i) {
              if (ERR[i] > threshold && mesh.points()[mesh.ind_points_of_convex(i)[0]][0] >= -0.1)
                conv_to_refine.add(i);
              min_ = std::min(min_, ERR[i]);
            }
            cout << "min = " << min_ << endl;
            cout << "Refining " <<  conv_to_refine.card() << " convexes..."<< endl;
            mesh.Bank_refine(conv_to_refine);

          }
          else
            break;

        }
        if (mode_counter == 1) {
          mesh.write_to_file(datafilename + ".meshh");
          cout << "Refining process complete. The mesh contains now " <<  mesh.convex_index().size() << " convexes "<<endl;

          blocked_dof = mf_u().basic_dof_on_region(5);
          mf_printed.set_finite_element(mesh.convex_index(),
                                        getfem::fem_descriptor(FEM_DISC));
        } else break;
      } while (adapted_refine && conv_to_refine.size() > 0 );


      plain_vector W1(mf_printed.nb_dof());
      plain_vector W2(mf_printed.nb_dof());
      cout << "nb of dof of printed_dof = " << mf_printed.nb_dof() << "." << endl;
      cout << "Assembling final solution using the mode " << mode_counter << " solution..." << endl;
      cout << "size of W1 and W2 = " << W1.size() << "." << endl;

      switch (mode_counter){

      case 1:{
        W12.resize(mf_printed.nb_dof()*2);
        getfem::interpolation(mf_u(), mf_printed, U, W1);
        size_type j = 0;
        for(size_type i=0; i < W1.size(); i++){
          W12[j] = W1[i];
          j=j+2;
        }
        cout << "W1[0]= " << W1[0] << "W1[1]= " << W1[1] << "W1[2]= " << W1[2] << "W1[3]= " << W1[3] << endl;
        cout << "W12[0]= " << W12[0] << " W12[1]= " << W12[1] << " W12[2]= " << W12[2] << " W12[3]= " << W12[3] << " W12[4]= " << W12[4] <<  " W12[5]= " << W12[5] <<  " W12[6]= " << W12[6]  << endl;
      } break;

      case 2:{
        size_type j = 0;
        getfem::interpolation(mf_u(), mf_printed, U, W2);
        for(size_type i=0; i < W2.size(); i++){
          W12[j+1] = W2[i];
          j = j+2;
        }
      } break;
      }


      mode_counter++;
    } while(mode_counter < 3);
    mf_printed.write_to_file(datafilename + "12.meshfem_", true);
    mf_printed.set_qdim(4);
    mf_printed.write_to_file(datafilename + "12.meshfem", true);
    gmm::vecsave(datafilename + "12.U", W12);

    cout << "size of W12 = " << W12.size() << "." << endl;

  } break;

  }
  return (iteration);

}


/**************************************************************************/
/*  main program.                                                         */
/**************************************************************************/

int main(int argc, char *argv[]) {

  GMM_SET_EXCEPTION_DEBUG; // Exceptions make a memory fault, to debug.
  FE_ENABLE_EXCEPT;        // Enable floating point exception for Nan.

  //getfem::getfem_mesh_level_set_noisy();


  try {
    crack_problem p;
    p.PARAM.read_command_line(argc, argv);
    p.init();
    p.mesh.write_to_file(p.datafilename + ".mesh");
    plain_vector U(p.mf_u().nb_dof());
     if (!p.solve(U)) GMM_ASSERT1(false, "Solve has failed");

    {
      getfem::mesh mcut;
      p.mls.global_cut_mesh(mcut);
      unsigned Q = p.mf_u().get_qdim();
      getfem::mesh_fem mf(mcut, dim_type(Q));
      mf.set_classical_discontinuous_finite_element(2, 0.001);
      // mf.set_finite_element
      //        (getfem::fem_descriptor("FEM_PK_DISCONTINUOUS(2, 2, 0.0001)"));
      plain_vector V(mf.nb_dof());

      getfem::interpolation(p.mf_u(), mf, U, V);

      getfem::stored_mesh_slice sl;
      getfem::mesh mcut_refined;

      unsigned NX = unsigned(p.PARAM.int_value("NX")), nn;
      if (NX < 6) nn = 24;
      else if (NX < 12) nn = 8;
      else if (NX < 30) nn = 3;
      else nn = 1;

      /* choose an adequate slice refinement based on the distance to the crack tip */
      std::vector<bgeot::short_type> nrefine(mcut.convex_index().last_true()+1);
      for (dal::bv_visitor cv(mcut.convex_index()); !cv.finished(); ++cv) {
        scalar_type dmin=0, d;
        base_node Pmin,P;
        for (unsigned i=0; i < mcut.nb_points_of_convex(cv); ++i) {
          P = mcut.points_of_convex(cv)[i];
          d = gmm::vect_norm2(ls_function(P));
          if (d < dmin || i == 0) { dmin = d; Pmin = P; }
        }

        if (dmin < 1e-5)
          nrefine[cv] = short_type(nn*8);
        else if (dmin < .1)
          nrefine[cv] = short_type(nn*2);
        else nrefine[cv] = short_type(nn);
        if (dmin < .01)
          cout << "cv: "<< cv << ", dmin = " << dmin << "Pmin=" << Pmin << " " << nrefine[cv] << "\n";
      }

      {
        getfem::mesh_slicer slicer(mcut);
        getfem::slicer_build_mesh bmesh(mcut_refined);
        slicer.push_back_action(bmesh);
        slicer.exec(nrefine, getfem::mesh_region::all_convexes());
      }
      /*
      sl.build(mcut,
      getfem::slicer_build_mesh(mcut_refined), nrefine);*/

      getfem::mesh_im mim_refined(mcut_refined);
      mim_refined.set_integration_method(getfem::int_method_descriptor
                                         ("IM_TRIANGLE(6)"));

      getfem::mesh_fem mf_refined(mcut_refined, dim_type(Q));
      mf_refined.set_classical_discontinuous_finite_element(2, 0.0001);
      plain_vector W(mf_refined.nb_dof());

      getfem::interpolation(p.mf_u(), mf_refined, U, W);

#ifdef VALIDATE_XFEM
      p.exact_sol.mf.set_qdim(dim_type(Q));
      assert(p.exact_sol.mf.nb_dof() == p.exact_sol.U.size());
      plain_vector EXACT(mf_refined.nb_dof());
      getfem::interpolation(p.exact_sol.mf, mf_refined,
                            p.exact_sol.U, EXACT);

      plain_vector DIFF(EXACT); gmm::add(gmm::scaled(W,-1),DIFF);
#endif

      if (p.PARAM.int_value("VTK_EXPORT")) {
        getfem::mesh_fem mf_refined_vm(mcut_refined, 1);
        mf_refined_vm.set_classical_discontinuous_finite_element(1, 0.0001);
        cerr << "mf_refined_vm.nb_dof=" << mf_refined_vm.nb_dof() << "\n";
        plain_vector VM(mf_refined_vm.nb_dof());

        cout << "computing von mises\n";
        getfem::interpolation_von_mises(mf_refined, mf_refined_vm, W, VM);

        plain_vector D(mf_refined_vm.nb_dof() * Q),
          DN(mf_refined_vm.nb_dof());

#ifdef VALIDATE_XFEM
        getfem::interpolation(mf_refined, mf_refined_vm, DIFF, D);
        for (unsigned i=0; i < DN.size(); ++i) {
          DN[i] = gmm::vect_norm2(gmm::sub_vector(D, gmm::sub_interval(i*Q, Q)));
        }
#endif

        cout << "export to " << p.datafilename + ".vtk" << "..\n";
        getfem::vtk_export exp(p.datafilename + ".vtk",
                               p.PARAM.int_value("VTK_EXPORT")==1);
        exp.exporting(mf_refined);
        //exp.write_point_data(mf_refined_vm, DN, "error");
        exp.write_point_data(mf_refined_vm, VM, "von mises stress");
        exp.write_point_data(mf_refined, W, "elastostatic_displacement");

#ifdef VALIDATE_XFEM

        plain_vector VM_EXACT(mf_refined_vm.nb_dof());


        getfem::interpolation_von_mises(mf_refined, mf_refined_vm, EXACT, VM_EXACT);
        getfem::vtk_export exp2("bimaterial_crack_exact.vtk");
        exp2.exporting(mf_refined);
        exp2.write_point_data(mf_refined_vm, VM_EXACT, "exact von mises stress");
        exp2.write_point_data(mf_refined, EXACT, "reference solution");

#endif

        cout << "export done, you can view the data file with (for example)\n"
          "mayavi -d " << p.datafilename << ".vtk -f "
          "WarpVector -m BandedSurfaceMap -m Outline\n";
      }


#ifdef VALIDATE_XFEM
      cout << "L2 ERROR:"<< getfem::asm_L2_dist(p.mim, p.mf_u(), U,
                                                p.exact_sol.mf, p.exact_sol.U)
           << endl << "H1 ERROR:"
           << getfem::asm_H1_dist(p.mim, p.mf_u(), U,
                                  p.exact_sol.mf, p.exact_sol.U) << "\n";

      /* cout << "OLD ERROR L2:"
         << getfem::asm_L2_norm(mim_refined,mf_refined,DIFF)
         << " H1:" << getfem::asm_H1_dist(mim_refined,mf_refined,
         EXACT,mf_refined,W)  << "\n";

         cout << "ex = " << p.exact_sol.U << "\n";
         cout << "U  = " << gmm::sub_vector(U, gmm::sub_interval(0,8)) << "\n";
      */
#endif
    }

  }
  GMM_STANDARD_CATCH_ERROR;

  return 0;
}



