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MatrixMarket_util.hpp
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00041 
00042 #ifndef __MatrixMarket_util_hpp
00043 #define __MatrixMarket_util_hpp
00044 
00045 #include <Teuchos_as.hpp>
00046 #include <string>
00047 
00048 namespace Tpetra {
00049   namespace MatrixMarket {
00050 
00051     namespace details {
00052 
00074       template<class Scalar>
00075       class SetScientific {
00076       public:
00077   typedef Scalar scalar_type;
00078 
00083   SetScientific (std::ostream& out) : 
00084     out_ (out), originalFlags_ (out.flags()) 
00085   {
00086     typedef Teuchos::ScalarTraits<scalar_type> STS;
00087     typedef typename STS::magnitudeType magnitude_type;
00088     typedef Teuchos::ScalarTraits<magnitude_type> STM;
00089 
00090     // Print floating-point values in scientific notation.
00091     out << std::scientific;
00092 
00093     // We're writing decimal digits, so compute the number of
00094     // digits we need to get reasonable accuracy when reading
00095     // values back in.
00096     //
00097     // There is actually an algorithm, due to Guy Steele (yes,
00098     // Java's Guy Steele) et al., for idempotent printing of
00099     // finite-length floating-point values.  We should actually
00100     // implement that algorithm, but I don't have time for that
00101     // now.  Currently, I just print no more than (one decimal
00102     // digit more than (the number of decimal digits justified
00103     // by the precision of magnitude_type)).
00104     //
00105     // We need to use STM's log10() rather than (say) std::log10
00106     // here, because STM::base() returns a magnitude_type, not
00107     // one of C++'s standard integer types.
00108     const magnitude_type numDecDigits = STM::t() * STM::log10 (STM::base());
00109 
00110     // Round and add one.  The cast to int should not overflow
00111     // unless STM::t() is _extremely_ large, so we don't need to
00112     // check for that case here.
00113     const magnitude_type one = STM::one();
00114     const magnitude_type two = one + one;
00115           // Cast from magnitude_type to int, since std::ostream's
00116           // precision() method expects an int input.
00117     const int prec = 1 + Teuchos::as<int> ((two*numDecDigits + one) / two);
00118     
00119     // Set the number of (decimal) digits after the decimal
00120     // point to print.
00121     out.precision (prec);
00122   } 
00123 
00129   ~SetScientific () {
00130     out_.flags (originalFlags_);
00131   }
00132 
00133       private:
00135   std::ostream& out_;
00136 
00138   std::ios_base::fmtflags originalFlags_;
00139       };
00140 
00141       // We define a class because template functions can't (in the
00142       // current C++ standard) have default template parameters.
00143       template<class Scalar, bool isComplex=Teuchos::ScalarTraits<Scalar>::isComplex>
00144       class ScalarAssigner {
00145       public:
00146   static void
00147   assign (Scalar& val,
00148     const typename Teuchos::ScalarTraits<Scalar>::magnitudeType& real,
00149     const typename Teuchos::ScalarTraits<Scalar>::magnitudeType& imag);
00150       };
00151 
00152       template<class RealType>
00153       class ScalarAssigner<RealType, false> {
00154       public:
00155   static void
00156   assign (RealType& val,
00157     const typename Teuchos::ScalarTraits<RealType>::magnitudeType& real,
00158     const typename Teuchos::ScalarTraits<RealType>::magnitudeType& imag)
00159   {
00160     // imag had better be zero.  We're ignoring it regardless.
00161     (void) imag;
00162     val = real; 
00163   }
00164       };
00165 
00166 #ifdef HAVE_TEUCHOS_COMPLEX
00167       template<class MagType>
00168       class ScalarAssigner<std::complex<MagType>, true> {
00169       public:
00170   static void
00171   assign (std::complex<MagType>& val,
00172     const typename Teuchos::ScalarTraits<std::complex<MagType> >::magnitudeType& real,
00173     const typename Teuchos::ScalarTraits<std::complex<MagType> >::magnitudeType& imag)
00174   {
00175     val = std::complex<MagType> (real, imag);
00176   }
00177       };
00178 #endif // HAVE_TEUCHOS_COMPLEX
00179 
00180       // \fn assignScalar
00181       // \brief val = S(real, imag).
00182       //
00183       // We have to template it because we don't know that S is a
00184       // complex type; if we write S(real,imag), the compiler will
00185       // complain if S is a real type.
00186       template<class Scalar>
00187       void 
00188       assignScalar (Scalar& val, 
00189         const typename Teuchos::ScalarTraits<Scalar>::magnitudeType& real,
00190         const typename Teuchos::ScalarTraits<Scalar>::magnitudeType& imag)
00191       {
00192   ScalarAssigner<Scalar>::assign (val, real, imag);
00193       }
00194 
00195     } // namespace details
00196 
00197 
00198     static bool isSkew (const std::string& symmType) {
00199       return symmType.size() >= 4 && symmType.substr(0,4) == "skew";
00200     }
00201     static bool isConj (const std::string& symmType) {
00202       return std::string::npos != symmType.find ("hermitian");
00203     }
00204     static bool needsSymmetrization (const std::string& symmType) {
00205       return symmType != "general";
00206     }
00207 
00219     template<class AdderType>
00220     class SymmetrizingAdder {
00221     public:
00222       typedef typename AdderType::index_type index_type;
00223       typedef typename AdderType::value_type value_type;
00224     
00225       SymmetrizingAdder (const Teuchos::RCP<AdderType>& adder, 
00226        const std::string& symmType) :
00227   adder_ (adder),
00228   symmetrize_ (needsSymmetrization (symmType)),
00229   conjugate_ (isConj (symmType)),
00230   skew_ (isSkew (symmType))
00231       {}
00232 
00233 
00234     
00235       void operator() (const index_type i, const index_type j, const value_type& Aij) {
00236   AdderType& theAdder = *adder_;
00237 
00238   theAdder (i, j, Aij);
00239   if (symmetrize_ && i != j) {
00240     typedef Teuchos::ScalarTraits<value_type> STS;
00241     const value_type Aji = skew_ ? 
00242       -(conjugate_ ? STS::conjugate(Aij) : Aij) : 
00243       (conjugate_ ? STS::conjugate(Aij) : Aij);
00244     theAdder (j, i, Aji);
00245   }
00246       }
00247 
00251       Teuchos::RCP<AdderType> getAdder() const {
00252   return adder_;
00253       }
00254 
00255     private:
00256       Teuchos::RCP<AdderType> adder_;
00257       bool symmetrize_, conjugate_, skew_;
00258     };
00259 
00260   } // namespace MatrixMarket
00261 } // namespace Tpetra
00262 
00263 #endif // __MatrixMarket_util_hpp
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