ex1.c

一个用来实现偏微分方程中网格的计算库

/* $Id: ex1.C 2837 2008-05-08 17:23:37Z roystgnr $ */

/* The Next Great Finite Element Library. */
/* Copyright (C) 2003  Benjamin S. Kirk */

/* This library 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 2.1 of the License, or (at your option) any later version. */

/* This library 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 for more details. */

/* You should have received a copy of the GNU Lesser General Public */
/* License along with this library; if not, write to the Free Software */
/* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA */

 // <h1>Example 1 - Creation of a Mesh Object</h1>
 // 
 // This is the first example program.  It simply demonstrates
 // how to create a mesh object.  A mesh is read from file,
 // information is printed to the screen, and the mesh is then
 // written.

 // C++ include files that we need
#include <iostream>
// Functions to initialize the library.
#include "libmesh.h"
// Basic include files needed for the mesh functionality.
#include "mesh.h"

int main (int argc, char** argv)
{
  // Initialize the library.  This is necessary because the library
  // may depend on a number of other libraries (i.e. MPI  and Petsc)
  // that require initialization before use.  When the LibMeshInit
  // object goes out of scope, other libraries and resources are
  // finalized.
  LibMeshInit init (argc, argv);

  // Check for proper usage. The program is designed to be run
  // as follows:
  // ./ex1 -d DIM input_mesh_name [output_mesh_name]
  // where [output_mesh_name] is an optional parameter giving
  // a filename to write the mesh into.
  if (argc < 4)
    {
      if (libMesh::processor_id() == 0)
        std::cerr << "Usage: " << argv[0] << " -d 2 in.mesh [out.mesh]"
                  << std::endl;
      
      // This handy function will print the file name, line number,
      // and then abort.  Currently the library does not use C++
      // exception handling.
      libmesh_error();
    }
  
  // Get the dimensionality of the mesh from argv[2]
  const unsigned int dim = std::atoi(argv[2]);
  
  // Create a mesh with the requested dimension.
  Mesh mesh(dim);
  
  // Read the input mesh.
  mesh.read (argv[3]);
  
  mesh.find_neighbors();

  // Print information about the mesh to the screen.
  mesh.print_info();
  
  // Write the output mesh if the user specified an
  // output file name.
  if (argc == 5)
    mesh.write (argv[4]);

  // All done.  libMesh objects are destroyed here.  Because the
  // LibMeshInit object was created first, its destruction occurs
  // last, and it's destructor finalizes any external libraries and
  // checks for leaked memory.
  return 0;
}