Teuchos - Trilinos Tools Package Version of the Day
Teuchos_MatrixMarket_SymmetrizingAdder.hpp
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00041 
00042 #ifndef __Teuchos_MatrixMarket_SymmetrizingAdder_hpp
00043 #define __Teuchos_MatrixMarket_SymmetrizingAdder_hpp
00044 
00045 #include <Teuchos_as.hpp>
00046 #include <Teuchos_ScalarTraits.hpp>
00047 #include <string>
00048 
00049 
00050 namespace Teuchos {
00051   namespace MatrixMarket {
00052     // Anonymous namespace for helper functions for SymmetrizingAdder.
00053     namespace {
00054       bool isSkew (const std::string& symmType) {
00055         return symmType.size() >= 4 && symmType.substr(0,4) == "skew";
00056       }
00057 
00058       bool isConj (const std::string& symmType) {
00059         return std::string::npos != symmType.find ("hermitian");
00060       }
00061 
00062       bool needsSymmetrization (const std::string& symmType) {
00063         return symmType != "general";
00064       }
00065     } // namespace (anonymous)
00066 
00086     template<class AdderType>
00087     class SymmetrizingAdder {
00088     public:
00090       typedef typename AdderType::index_type index_type;
00092       typedef typename AdderType::value_type value_type;
00093 
00100       SymmetrizingAdder (const Teuchos::RCP<AdderType>& adder,
00101                          const std::string& symmType) :
00102         adder_ (adder),
00103         symmetrize_ (needsSymmetrization (symmType)),
00104         conjugate_ (isConj (symmType)),
00105         skew_ (isSkew (symmType))
00106       {}
00107 
00109       void
00110       operator() (const index_type i,
00111                   const index_type j,
00112                   const value_type& Aij)
00113       {
00114         AdderType& theAdder = *adder_;
00115 
00116         theAdder (i, j, Aij);
00117         if (symmetrize_ && i != j) {
00118           typedef Teuchos::ScalarTraits<value_type> STS;
00119           const value_type Aji = skew_ ?
00120             -(conjugate_ ? STS::conjugate(Aij) : Aij) :
00121             (conjugate_ ? STS::conjugate(Aij) : Aij);
00122           // The optional fourth argument (which defaults to true)
00123           // specifies whether or not to count the entry against the
00124           // total expected number of entries.  We don't want to count
00125           // this entry because it wasn't part of the original data;
00126           // we inserted it because the caller doesn't want symmetric
00127           // storage.  The original data's total expected number of
00128           // entries only counts the entries that are in the original
00129           // data, not those that we insert.
00130           theAdder (j, i, Aji, false);
00131         }
00132       }
00133 
00137       Teuchos::RCP<AdderType> getAdder() const {
00138         return adder_;
00139       }
00140 
00141     private:
00143       Teuchos::RCP<AdderType> adder_;
00145       bool symmetrize_;
00147       bool conjugate_;
00149       bool skew_;
00150     };
00151 
00152   } // namespace MatrixMarket
00153 } // namespace Teuchos
00154 
00155 #endif // __Teuchos_MatrixMarket_SymmetrizingAdder_hpp
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