optimisation/linear_vs_nonlinear/two_d_poisson.cc File Reference

#include "generic.h"
#include "poisson.h"
#include "meshes/simple_rectangular_quadmesh.h"

Classes
class	PoissonProblem< ELEMENT >
	Micky mouse Poisson problem. More...

Namespaces
	TanhSolnForPoisson
	Namespace for exact solution for Poisson equation with "sharp step".

Functions
void	TanhSolnForPoisson::get_exact_u (const Vector< double > &x, Vector< double > &u)
	Exact solution as a Vector. More...
void	TanhSolnForPoisson::source_function (const Vector< double > &x, double &source)
	Source function required to make the solution above an exact solution. More...
int	main (int argc, char *argv[])
	Driver code for 2D Poisson problem. More...

Function Documentation

main()

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

Driver code for 2D Poisson problem.

{
 
 
 // Number of uniform refinements relative to a 2x2 base mesh
 unsigned n_refine;
 
 // Get number of refinement levels from command line or use default
 if (argc==1)
  {
   n_refine=5;
  }
 else if (argc==2)
  {
   n_refine=atoi(argv[1]);
  }
 else
  {
   std::string error_message =
    "Wrong number of input arguments. The options are: \n";
   error_message +=
    "No args: Default number of refinements\n";
   error_message +=
    "One arg: Required number of refinements\n";
 
   throw OomphLibError(error_message,
                       OOMPH_CURRENT_FUNCTION,
                       OOMPH_EXCEPTION_LOCATION);
  }
 
 //Set up the problem
 //------------------
 
 //  Initialise timers
 clock_t t_start = clock();
 
 // Create the problem with 2D nine-node elements from the
 // QPoissonElement family. Pass pointer to source function
 // and number of refinements required
 PoissonProblem<QPoissonElement<2,3> > 
  problem(&TanhSolnForPoisson::source_function,n_refine);
 
 // Finish/doc timing
 clock_t t_end = clock();
 double total_time=double(t_end-t_start)/CLOCKS_PER_SEC;
 cout << std::endl;
 cout << "======================================================= " << std::endl;
 cout << "Total time for Problem setup [sec]: " << total_time << std::endl;
 cout << "======================================================= " << std::endl;
 cout << std::endl;
 
 // Create label for output
 //------------------------
 DocInfo doc_info;
 
 // Set output directory
 doc_info.set_directory("RESLT");
 
 // Step number
 doc_info.number()=0;
 
 
 // Set the orientation of the "step" to 45 degrees
 TanhSolnForPoisson::TanPhi=1.0;
 
 // Initial value for the steepness of the "step"
 TanhSolnForPoisson::Alpha=1.0; 
 
 
 // Solve as linear and nonlinear problem
 //--------------------------------------
 problem.set_problem_is_nonlinear();
 
 unsigned nstep=2;
 for (unsigned istep=0;istep<nstep;istep++)
  {
 
   //  Initialise timers
   clock_t t_start = clock();
 
   if (problem.is_problem_nonlinear())
    {
     cout << std::endl << std::endl;
     cout << "============================ " << std::endl;
     cout << "Solving as nonlinear problem " << std::endl;
     cout << "============================ " << std::endl;
     cout << std::endl << std::endl;
    }
   else
    {
     cout << std::endl << std::endl;
     cout << "============================ " << std::endl;
     cout << "Solving as linear problem " << std::endl;
     cout << "============================ " << std::endl;
     cout << std::endl << std::endl;
    }
 
 
   // Solve the problem
   problem.newton_solve();
 
   // Finish/doc timing
   clock_t t_end = clock();
   double total_time=double(t_end-t_start)/CLOCKS_PER_SEC;
   cout << "======================================================= " << std::endl;
   cout << "Total time for Newton solve [sec]: " << total_time << std::endl;
   cout << "======================================================= " << std::endl;
 
   //Output the solution
   problem.doc_solution(doc_info);
 
   //Increment counter for solutions 
   doc_info.number()++;
 
   // Next time around solve as linear problem
   problem.set_problem_is_linear();
 
  }
 
 
 // Give user a chance to check the memory usage
 cout << std::endl << std::endl;
 cout << "Execution is paused while problem is in core" << std::endl;
 pause("Have a look at the memory usage now"); 
 
 
} //end of main

References TanhSolnForPoisson::Alpha, oomph::DocInfo::number(), OOMPH_CURRENT_FUNCTION, OOMPH_EXCEPTION_LOCATION, oomph::pause(), problem, oomph::DocInfo::set_directory(), TanhSolnForPoisson::source_function(), oomph::Global_string_for_annotation::string(), and TanhSolnForPoisson::TanPhi.