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Viewing changes to examples/gsl1d_nl_1.cpp

  • Committer: Apostol Faliagas
  • Date: 2019-02-12 21:52:42 UTC
  • Revision ID: apostol.faliagas@gmail.com-20190212215242-mua2h96aikfvog8y
Published version 0.1

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examples/gsl1d_nl_1.cpp
 
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#include <iostream>
 
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#include "pde1d.hpp"
 
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using namespace fd;
 
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using namespace fd1;
 
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const char *project_info =
 
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R"(//!  Project: Nonlinear PDE-1d with Dirichlet BCs, No. 1
 
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//!
 
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//!    --+----------+-----> x
 
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//!      0          1
 
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//!     [b0]       [b1]
 
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//!
 
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//! PDE:
 
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//!     $u_{xx}-2*u^2=0$
 
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//!
 
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//! BCs:
 
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//! b0: $0$
 
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//! b1: $1$
 
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//!
 
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//!     Exact solutions:
 
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//!     $u_1(x)=\frac{3}{(2+x)^2}$
 
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//!     $u_2(x)=?$
 
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//!
 
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//! Boundary discretization method: does not apply
 
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//! Linear solver: GSL all but GMRES (it does not work).
 
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//! Nonlinear solver: GSL all.
 
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)";
 
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int main()
 
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{
 
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        try
 
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        {
 
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                Boundary b0(0.);
 
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                Boundary b1(1.);
 
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                Mesh mesh(50);
 
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                mesh.set_boundaries({b0, b1});
 
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                DirichletBC bc0(b0, "0.75"), bc1(b1, "0.333333333333333333");
 
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                // Part 1: declaration of fields and functions
 
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                Field u("u");
 
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                Function f("f");
 
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                Function a("fa"), b("fb"), xs("exact_solution");
 
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                // Part 2: declaration and customization of PDE
 
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                PDE pde(&mesh);
 
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                pde.name = "PDE1d";
 
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                pde.boundary_discretization_method = PDE::/*SYM_DIFF2;*/INWARD_DIFF3;
 
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                // Part 3: set PDE fields, BCs and functions
 
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                pde.set_field(u);
 
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                pde.set_BCs({bc1, bc0}, u);
 
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                pde.set_functions({f, a, b, xs});
 
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                a.set_implementation("0");
 
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                b.set_implementation("1./3.");
 
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                f.set_implementation("0");
 
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                xs.set_implementation("3/((2+x)*(2+x))");
 
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                // Part 4: set PDE equations
 
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                pde = Dxx[u] - 2.*u*u;
 
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                std::cout << "PDE";
 
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                std::cout << (pde.linear_BCs() ? " has linear BCs" : " has nonlinear BCs") << '\n';
 
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                std::cout << "PDE";
 
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                std::cout << (pde.linear_eqs() ? " has linear eqs" : " has nonlinear eqs") << '\n';
 
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                std::cout << "PDE";
 
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                std::cout << (pde.linear() ? " is linear." : " is nonlinear.") << '\n';
 
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                // Part 5: set methods
 
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                pde.set_library("gsl");
 
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                pde.set_matrix_method("LU");
 
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                // hybrids, hybrid, dnewton, broyden, hybridsj, hybridj, newton, gnewton
 
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                pde.set_nonlinear_solver("newton");
 
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                // Part 6: output
 
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                pde.executable = "gsl1d_nl_1";
 
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                pde.compiler = "clang++";
 
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                pde.project_info = project_info;
 
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                pde.set_output("code/gsl1d_nl_1");
 
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                pde.generate_code();
 
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                pde.generate_makefile();
 
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        }
 
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        catch (const std::string& msg)
 
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        {
 
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                std::cout << msg << std::endl;
 
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                exit(1);
 
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        }
 
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        catch (const char *msg)
 
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        {
 
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                std::cout << "Caught const char* exception!\n";
 
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                std::cout << msg << std::endl;
 
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                exit(1);
 
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        }
 
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        return 0;
 
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}