laptopbig.edp

FreeFem++可以生成高质量的有限元网格。可以用于流体力学

//  a example to test the level of optimisation
// --------------------------------------------
int nn=2000;
real cpu=0; 
 mesh Th=square(nn,nn);
verbosity=10;
 fespace Vh(Th,P1);     // P1 FE space
 Vh uh,vh;              // unkown and test function. 
 func f=1;                 //  right hand side function 
 func g=0;                 //  boundary condition function

  problem laplace2(uh,vh,solver=UMFPACK,tgv=1e30) =                    //  definion of  the problem 
    int2d(Th)( dx(uh)*dx(vh) + dy(uh)*dy(vh) ) //  bilinear form
    + int1d(Th,1)( uh*vh) 
    + int1d(Th,1)( - vh)
    + int2d(Th)( -f*vh )                          //  linear form
    + on(2,3,4,uh=g) ;                      //  boundary condition form

  cpu=clock(); 
  laplace2; // solve the problem plot(uh); // to see the result
  cout << "-- lap UMFPACK  " << nn << "x" << nn << "  : "
       <<  -cpu+clock() << " s,  max =" << uh[].max << endl;

//  plot(uh,ps="lap1-cpu.eps",value=true);