MOAB: Mesh Oriented datABase  (version 5.2.1)
TUntangle1.cpp
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00001 /* *****************************************************************
00002     MESQUITE -- The Mesh Quality Improvement Toolkit
00003 
00004     Copyright 2009 Sandia National Laboratories.  Developed at the
00005     University of Wisconsin--Madison under SNL contract number
00006     624796.  The U.S. Government and the University of Wisconsin
00007     retain certain rights to this software.
00008 
00009     This library is free software; you can redistribute it and/or
00010     modify it under the terms of the GNU Lesser General Public
00011     License as published by the Free Software Foundation; either
00012     version 2.1 of the License, or (at your option) any later version.
00013 
00014     This library is distributed in the hope that it will be useful,
00015     but WITHOUT ANY WARRANTY; without even the implied warranty of
00016     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00017     Lesser General Public License for more details.
00018 
00019     You should have received a copy of the GNU Lesser General Public License
00020     (lgpl.txt) along with this library; if not, write to the Free Software
00021     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00022 
00023     (2009) kraftche@cae.wisc.edu
00024 
00025   ***************************************************************** */
00026 
00027 /** \file TUntangle1.cpp
00028  *  \brief
00029  *  \author Jason Kraftcheck
00030  */
00031 
00032 #include "Mesquite.hpp"
00033 #include "TUntangle1.hpp"
00034 #include "TMPDerivs.hpp"
00035 #include "TMPCommon.hpp"
00036 
00037 #include <iostream>
00038 
00039 namespace MBMesquite
00040 {
00041 
00042 TUntangle1::~TUntangle1() {}
00043 
00044 std::string TUntangle1::get_name() const
00045 {
00046     return "Untangle1";
00047 }
00048 
00049 template < unsigned DIM >
00050 inline bool TUntangle1::eval( const MsqMatrix< DIM, DIM >& T, double& result )
00051 {
00052     double tau = det( T );
00053     result     = 0.5 * ( sqrt( tau * tau + mFactor ) - tau );
00054     return true;
00055 }
00056 
00057 template < unsigned DIM >
00058 inline bool TUntangle1::grad( const MsqMatrix< DIM, DIM >& T, double& result, MsqMatrix< DIM, DIM >& deriv_wrt_T )
00059 {
00060     double tau = det( T );
00061     double g   = sqrt( tau * tau + mFactor );
00062     if( g > 1e-50 )
00063     {
00064         double f    = tau / g - 1;
00065         result      = 0.5 * ( g - tau );
00066         deriv_wrt_T = transpose_adj( T );
00067         deriv_wrt_T *= 0.5 * f;
00068         return true;
00069     }
00070     else
00071     {
00072         std::cout << "Warning: Division by zero avoided in TUntangle1::grad()" << std::endl;
00073         return false;
00074     }
00075 }
00076 
00077 template < unsigned DIM >
00078 inline bool TUntangle1::hess( const MsqMatrix< DIM, DIM >& T, double& result, MsqMatrix< DIM, DIM >& deriv_wrt_T,
00079                               MsqMatrix< DIM, DIM >* second_wrt_T )
00080 {
00081     const MsqMatrix< DIM, DIM > adjt = transpose_adj( T );
00082     double tau                       = det( T );
00083     double g                         = sqrt( tau * tau + mFactor );
00084     if( g == 0 ) return false;
00085     double f = 0.5 * ( tau / g - 1 );
00086     result   = 0.5 * ( g - tau );
00087 
00088     deriv_wrt_T = adjt;
00089     deriv_wrt_T *= f;
00090 
00091     set_scaled_outer_product( second_wrt_T, 0.5 * mFactor / ( g * g * g ), adjt );
00092     pluseq_scaled_2nd_deriv_of_det( second_wrt_T, f, T );
00093 
00094     return true;
00095 }
00096 
00097 TMP_T_TEMPL_IMPL_COMMON( TUntangle1 )
00098 
00099 }  // namespace MBMesquite
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