CardiacNewtonSolver.hpp

00001 /*
00002 
00003 Copyright (C) University of Oxford, 2005-2009
00004 
00005 University of Oxford means the Chancellor, Masters and Scholars of the
00006 University of Oxford, having an administrative office at Wellington
00007 Square, Oxford OX1 2JD, UK.
00008 
00009 This file is part of Chaste.
00010 
00011 Chaste is free software: you can redistribute it and/or modify it
00012 under the terms of the GNU Lesser General Public License as published
00013 by the Free Software Foundation, either version 2.1 of the License, or
00014 (at your option) any later version.
00015 
00016 Chaste is distributed in the hope that it will be useful, but WITHOUT
00017 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
00018 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
00019 License for more details. The offer of Chaste under the terms of the
00020 License is subject to the License being interpreted in accordance with
00021 English Law and subject to any action against the University of Oxford
00022 being under the jurisdiction of the English Courts.
00023 
00024 You should have received a copy of the GNU Lesser General Public License
00025 along with Chaste. If not, see <http://www.gnu.org/licenses/>.
00026 
00027 */
00028 #ifndef CARDIACNEWTONSOLVER_HPP_
00029 #define CARDIACNEWTONSOLVER_HPP_
00030 
00031 #include <cmath>
00032 
00033 #include "AbstractBackwardEulerCardiacCell.hpp"
00034 
00047 template<unsigned SIZE>
00048 class CardiacNewtonSolver
00049 {
00050 public:
00056     static CardiacNewtonSolver<SIZE>* Instance()
00057     {
00058         static CardiacNewtonSolver<SIZE> inst;
00059         return &inst;
00060     }
00061 
00068     void Solve(AbstractBackwardEulerCardiacCell<SIZE> &rCell,
00069                double rCurrentGuess[SIZE])
00070     {
00071         unsigned counter = 0;
00072 //        const double eps = 1e-6 * rCurrentGuess[0]; // Our tolerance (should use min(guess) perhaps?)
00073         const double eps = 1e-6; // JonW tolerance
00074         double norm = 2*eps;
00075 
00076         // check that the initial guess that was given gives a valid residual
00077         rCell.ComputeResidual(rCurrentGuess, mResidual);
00078         for (unsigned i=0; i<SIZE; i++)
00079         {
00080             assert(!isnan(mResidual[i]));
00081         }
00082 
00083         while (norm > eps)
00084         {
00085             // Calculate Jacobian for current guess
00086             rCell.ComputeJacobian(rCurrentGuess, mJacobian);
00087 
00088 //            // Update norm (our style)
00089 //            norm = ComputeNorm(mResidual);
00090 
00091             // Solve Newton linear system
00092             SolveLinearSystem();
00093 
00094             // Update norm (JonW style)
00095             norm = ComputeNorm(mUpdate);
00096 
00097             // Update current guess and recalculate residual
00098             for (unsigned i=0; i<SIZE; i++)
00099             {
00100                 rCurrentGuess[i] -= mUpdate[i];
00101             }
00102             rCell.ComputeResidual(rCurrentGuess, mResidual);
00103 
00104             counter++;
00105             assert(counter < 15); // avoid infinite loops
00106         }
00107     }
00108 
00183 
00184 
00185 protected:
00186     CardiacNewtonSolver()
00187     {}
00188     CardiacNewtonSolver(const CardiacNewtonSolver<SIZE>&);
00189     CardiacNewtonSolver<SIZE>& operator= (const CardiacNewtonSolver<SIZE>&);
00190 
00194     double ComputeNorm(double vector[SIZE])
00195     {
00196         double norm = 0.0;
00197         for (unsigned i=0; i<SIZE; i++)
00198         {
00199             if (fabs(vector[i]) > norm)
00200             {
00201                 norm = fabs(vector[i]);
00202             }
00203         }
00204         return norm;
00205     }
00206 
00210     void SolveLinearSystem()
00211     {
00212         double fact;
00213         for (unsigned i=0; i<SIZE; i++)
00214         {
00215             for (unsigned ii=i+1; ii<SIZE; ii++)
00216             {
00217                 fact = mJacobian[ii][i]/mJacobian[i][i];
00218                 for (unsigned j=i; j<SIZE; j++)
00219                 {
00220                     mJacobian[ii][j] -= fact*mJacobian[i][j];
00221                 }
00222                 mResidual[ii] -= fact*mResidual[i];
00223             }
00224         }
00225         /*This must be int, since an unsigned down-loop wouldn't terminate*/
00226         for (int i=SIZE-1; i>=0; i--)
00227         {
00228             mUpdate[i] = mResidual[i];
00229             for (unsigned j=i+1; j<SIZE; j++)
00230             {
00231                 mUpdate[i] -= mJacobian[i][j]*mUpdate[j];
00232             }
00233             mUpdate[i] /= mJacobian[i][i];
00234         }
00235     }
00236 
00237 private:
00239     double mResidual[SIZE];
00241     double mJacobian[SIZE][SIZE];
00243     double mUpdate[SIZE];
00244 };
00245 
00246 #endif /*CARDIACNEWTONSOLVER_HPP_*/

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