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Tsqr_ScalarTraits.hpp
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00003 //
00004 //                 Anasazi: Block Eigensolvers Package
00005 //                 Copyright (2010) Sandia Corporation
00006 //
00007 // Under terms of Contract DE-AC04-94AL85000, there is a non-exclusive
00008 // license for use of this work by or on behalf of the U.S. Government.
00009 //
00010 // This library is free software; you can redistribute it and/or modify
00011 // it under the terms of the GNU Lesser General Public License as
00012 // published by the Free Software Foundation; either version 2.1 of the
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00015 // This library is distributed in the hope that it will be useful, but
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00017 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00018 // Lesser General Public License for more details.
00019 //
00020 // You should have received a copy of the GNU Lesser General Public
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00028 
00029 #ifndef __TSQR_Tsqr_ScalarTraits_hpp
00030 #define __TSQR_Tsqr_ScalarTraits_hpp
00031 
00032 #include <cmath> // std::abs
00033 #include <complex>
00034 
00037 
00038 namespace TSQR {
00039 
00059   template< class Scalar >
00060   class ScalarTraits {
00061   public:
00065     static const bool is_specialized = false;
00068     static const bool is_complex = false;
00074     typedef Scalar magnitude_type;
00077     static Scalar zero();
00080     static Scalar one();
00088     static magnitude_type pi() {
00089       return 6.2831853071795864769252867663e+0;
00090     }
00093     inline static Scalar conj (const Scalar& z);
00096     inline static magnitude_type abs (const Scalar& z);
00097   };
00098 
00099   template<>
00100   class ScalarTraits< double > {
00101   public:
00102     static const bool is_specialized = true;
00103     static const bool is_complex = false;
00104     typedef double magnitude_type;
00105 
00106     static double zero() { return 0.0; }
00107     static double one() { return 1.0; }
00108     static magnitude_type pi() {
00109       // In double precision, 17 digits suffice.  We include 20 just
00110       // for good measure.  Hopefully the C++ compiler won't do a
00111       // stupid thing with them.
00112       return 3.14159265358979323846;
00113     }
00114 
00115     inline static double conj (const double& z) { return z; }
00116     inline static magnitude_type abs (const double& z) {
00117       return std::abs (z);
00118     }
00119   };
00120 
00121   template<>
00122   class ScalarTraits< float > {
00123   public:
00124     static const bool is_specialized = true;
00125     static const bool is_complex = false;
00126     typedef float magnitude_type;
00127 
00128     static float zero() { return 0.0; }
00129     static float one() { return 1.0; }
00130     static magnitude_type pi() {
00131       return 3.14159265358979323846;
00132     }
00133 
00134     inline static float conj (const float& z) { return z; }
00135     inline static magnitude_type abs (const float& z) {
00136       return std::abs (z);
00137     }
00138   };
00139 
00140   template<>
00141   class ScalarTraits< std::complex< double > > {
00142   public:
00143     static const bool is_specialized = true;
00144     static const bool is_complex = true;
00145     typedef double magnitude_type;
00146 
00147     static std::complex<double> zero() { return std::complex<double>(0.0, 0.0); }
00148     static std::complex<double> one()  { return std::complex<double>(1.0, 0.0); }
00149     static magnitude_type pi() { return ScalarTraits< magnitude_type >::pi(); }
00150 
00151     inline static std::complex<double> conj (const std::complex<double>& z) {
00152       return std::conj (z);
00153     }
00154     inline static magnitude_type abs (const std::complex<double>& z) {
00155       return std::abs (z);
00156     }
00157   };
00158 
00159   template<>
00160   class ScalarTraits< std::complex< float > > {
00161   public:
00162     static const bool is_specialized = true;
00163     static const bool is_complex = true;
00164     typedef float magnitude_type;
00165 
00166     static std::complex<float> zero() { return std::complex<float>(0.0, 0.0); }
00167     static std::complex<float> one()  { return std::complex<float>(1.0, 0.0); }
00168     static magnitude_type pi() { return ScalarTraits< magnitude_type >::pi(); }
00169 
00170     inline static std::complex<float> conj (const std::complex<float>& z) {
00171       return std::conj (z);
00172     }
00173     inline static magnitude_type abs (const std::complex<float>& z) {
00174       return std::abs (z);
00175     }
00176   };
00177 
00178 
00179 } // namespace TSQR
00180 
00181 #endif // __TSQR_Tsqr_ScalarTraits_hpp
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