-- FreeFem++ v4.6 (Thu Apr  2 15:47:38 CEST 2020 - git v4.6)
 Load: lg_fem lg_mesh lg_mesh3 eigenvalue 
    1 : //  gnuplot_surface.edp
    2 : //
    3 : //  Discussion:
    4 : //
    5 : //    Write data to a file for processing by gnuplot.
    6 : //
    7 : //  Location:
    8 : //
    9 : //    http://people.sc.fsu.edu/~jburkardt/freefem++/gnuplot_surface/gnuplot_surface.edp
   10 : //
   11 : //  Licensing:
   12 : //
   13 : //    This code is distributed under the GNU LGPL license.
   14 : //
   15 : //  Modified:
   16 : //
   17 : //    20 August 2015
   18 : //
   19 : //  Author:
   20 : //
   21 : //    John Burkardt
   22 : //
   23 :   cout << "\n";
   24 :   cout << "GNUPLOT_SURFACE:\n";
   25 :   cout << "  FreeFem++ version:\n";
   26 :   cout << "  After solving a problem on a 2D region, write t
  ... : he data U(X,Y)\n";
   27 :   cout << "  to files that GNUPLOT can use to create a surfa
  ... : ce plot.\n";
   28 : //
   29 : //  Define the region.
   30 : //
   31 :   border domega ( t = 0.0, 2.0 * pi ) { x = cos(t); y = sin(t); }
   32 : 
   33 :   mesh Th = buildmesh ( domega ( 100 ) );
   34 : 
   35 :   plot ( Th, wait = 1, ps = "gnuplot_surface_mesh.ps" );
   36 : //
   37 : //  Define the finite element space.
   38 : //
   39 :   fespace Vh ( Th, P1 );
   40 :   Vh uh;
   41 :   Vh vh;
   42 : 
   43 :   func f = 1.0;
   44 :   real epsilon = 1.0E-02;
   45 : 
   46 :   solve poisson ( uh, vh, solver = LU ) =
   47 :     int2d ( Th ) ( dx ( uh ) * dx ( vh ) + dy ( uh ) * dy ( vh ) )
   48 :   + int1d ( Th, domega ) ( epsilon * uh * vh )
   49 :   - int2d ( Th ) ( f * vh );
   50 : //
   51 : //  Make a contour plot of UH.
   52 : //
   53 :   plot ( uh, nbiso = 50, fill = 0, value = 1.0, wait = 1, 
   54 :   ps = "gnuplot_surface_uh.ps" );
   55 : //
   56 : //  Write a data file for gnuplot.
   57 : //
   58 :   {
   59 :     ofstream data ( "gnuplot_surface_data.txt" );
   60 : 
   61 :     for ( int i = 0; i < Th.nt; i++ )
   62 :     {
   63 :       for ( int j = 0; j <= 3; j++ )
   64 :       {
   65 :         int j2 = ( j % 3 );
   66 :         data  << "  " << Th[i][j2].x 
   67 :               << "  " << Th[i][j2].y
   68 :               << "  " << uh[][Vh(i,j2)] << "\n";
   69 :       }
   70 :       data << "\n";
   71 :       data << "\n";
   72 :     }
   73 :     cout << "\n";
   74 :     cout << "Wrote gnuplot data file.\n";
   75 :   }
   76 : //
   77 : //  Write a command file for gnuplot.
   78 : //
   79 :   {
   80 :     ofstream commands ( "gnuplot_surface_commands.txt" );
   81 : 
   82 :     commands << "# gnuplot_surface_commands.txt\n";
   83 :     commands << "#\n";
   84 :     commands << "#  Usage:\n";
   85 :     commands << "#    gnuplot gnuplot_surface_commands.txt\n";
   86 :     commands << "#\n";
   87 :     commands << "set term png\n";
   88 :     commands << "set output 'gnuplot_surface.png'\n";
   89 :     commands << "set xlabel '<--- X --->'\n";
   90 :     commands << "set ylabel '<--- Y --->'\n";
   91 :     commands << "set zlabel '<--- Uh(X,Y) -->'\n";
   92 :     commands << "set title 'Surface plot created from FreeFem++ da
  ... : ta.'\n";
   93 :     commands << "unset key\n";
   94 :     commands << "set timestamp\n";
   95 :     commands << "splot 'gnuplot_surface_data.txt' with lines\n";
   96 :     commands << "quit\n";
   97 : 
   98 :     cout << "Wrote gnuplot command file.\n";
   99 :   }
  100 : //
  101 : //  Terminate.
  102 : //
  103 :   cout << "\n";
  104 :   cout << "GNUPLOT_SURFACE:\n";
  105 :   cout << "  Normal end of execution.\n";
  106 : 
  107 :  sizestack + 1024 =2408  ( 1384 )


GNUPLOT_SURFACE:
  FreeFem++ version:
  After solving a problem on a 2D region, write the data U(X,Y)
  to files that GNUPLOT can use to create a surface plot.
  --  mesh:  Nb of Triangles =   1750, Nb of Vertices 926
  SkyLineMatrix: size pL/pU: 926 28862 28862 moy=31.1685
  -- Solve : 
          min 49.9751  max 50.2254

Wrote gnuplot data file.
Wrote gnuplot command file.

GNUPLOT_SURFACE:
  Normal end of execution.
times: compile 0.005123s, execution 0.079785s,  mpirank:0
 CodeAlloc : nb ptr  3693,  size :478368 mpirank: 0
Ok: Normal End