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      1 // This file is part of a joint effort between Eigen, a lightweight C++ template library
      2 // for linear algebra, and MPFR C++, a C++ interface to MPFR library (http://www.holoborodko.com/pavel/)
      3 //
      4 // Copyright (C) 2010-2012 Pavel Holoborodko <pavel (a] holoborodko.com>
      5 // Copyright (C) 2010 Konstantin Holoborodko <konstantin (a] holoborodko.com>
      6 // Copyright (C) 2010 Gael Guennebaud <gael.guennebaud (a] inria.fr>
      7 //
      8 // This Source Code Form is subject to the terms of the Mozilla
      9 // Public License v. 2.0. If a copy of the MPL was not distributed
     10 // with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
     11 
     12 #ifndef EIGEN_MPREALSUPPORT_MODULE_H
     13 #define EIGEN_MPREALSUPPORT_MODULE_H
     14 
     15 #include <Eigen/Core>
     16 #include <mpreal.h>
     17 
     18 namespace Eigen {
     19   
     20 /**
     21   * \defgroup MPRealSupport_Module MPFRC++ Support module
     22   * \code
     23   * #include <Eigen/MPRealSupport>
     24   * \endcode
     25   *
     26   * This module provides support for multi precision floating point numbers
     27   * via the <a href="http://www.holoborodko.com/pavel/mpfr">MPFR C++</a>
     28   * library which itself is built upon <a href="http://www.mpfr.org/">MPFR</a>/<a href="http://gmplib.org/">GMP</a>.
     29   *
     30   * \warning MPFR C++ is licensed under the GPL.
     31   *
     32   * You can find a copy of MPFR C++ that is known to be compatible in the unsupported/test/mpreal folder.
     33   *
     34   * Here is an example:
     35   *
     36 \code
     37 #include <iostream>
     38 #include <Eigen/MPRealSupport>
     39 #include <Eigen/LU>
     40 using namespace mpfr;
     41 using namespace Eigen;
     42 int main()
     43 {
     44   // set precision to 256 bits (double has only 53 bits)
     45   mpreal::set_default_prec(256);
     46   // Declare matrix and vector types with multi-precision scalar type
     47   typedef Matrix<mpreal,Dynamic,Dynamic>  MatrixXmp;
     48   typedef Matrix<mpreal,Dynamic,1>        VectorXmp;
     49 
     50   MatrixXmp A = MatrixXmp::Random(100,100);
     51   VectorXmp b = VectorXmp::Random(100);
     52 
     53   // Solve Ax=b using LU
     54   VectorXmp x = A.lu().solve(b);
     55   std::cout << "relative error: " << (A*x - b).norm() / b.norm() << std::endl;
     56   return 0;
     57 }
     58 \endcode
     59   *
     60   */
     61 	
     62   template<> struct NumTraits<mpfr::mpreal>
     63     : GenericNumTraits<mpfr::mpreal>
     64   {
     65     enum {
     66       IsInteger = 0,
     67       IsSigned = 1,
     68       IsComplex = 0,
     69       RequireInitialization = 1,
     70       ReadCost = HugeCost,
     71       AddCost  = HugeCost,
     72       MulCost  = HugeCost
     73     };
     74 
     75     typedef mpfr::mpreal Real;
     76     typedef mpfr::mpreal NonInteger;
     77     
     78     static inline Real highest  (long Precision = mpfr::mpreal::get_default_prec()) { return  mpfr::maxval(Precision); }
     79     static inline Real lowest   (long Precision = mpfr::mpreal::get_default_prec()) { return -mpfr::maxval(Precision); }
     80 
     81     // Constants
     82     static inline Real Pi      (long Precision = mpfr::mpreal::get_default_prec())  { return mpfr::const_pi(Precision);        }
     83     static inline Real Euler   (long Precision = mpfr::mpreal::get_default_prec())  { return mpfr::const_euler(Precision);     }
     84     static inline Real Log2    (long Precision = mpfr::mpreal::get_default_prec())  { return mpfr::const_log2(Precision);      }
     85     static inline Real Catalan (long Precision = mpfr::mpreal::get_default_prec())  { return mpfr::const_catalan(Precision);   }
     86 
     87     static inline Real epsilon (long Precision = mpfr::mpreal::get_default_prec())  { return mpfr::machine_epsilon(Precision); }
     88     static inline Real epsilon (const Real& x)                                      { return mpfr::machine_epsilon(x); }
     89 
     90 #ifdef MPREAL_HAVE_DYNAMIC_STD_NUMERIC_LIMITS
     91     static inline int digits10 (long Precision = mpfr::mpreal::get_default_prec())  { return std::numeric_limits<Real>::digits10(Precision); }
     92     static inline int digits10 (const Real& x)                                      { return std::numeric_limits<Real>::digits10(x); }
     93 #endif
     94 
     95     static inline Real dummy_precision()
     96     {
     97       mpfr_prec_t weak_prec = ((mpfr::mpreal::get_default_prec()-1) * 90) / 100;
     98       return mpfr::machine_epsilon(weak_prec);
     99     }
    100   };
    101 
    102   namespace internal {
    103 
    104   template<> inline mpfr::mpreal random<mpfr::mpreal>()
    105   {
    106     return mpfr::random();
    107   }
    108 
    109   template<> inline mpfr::mpreal random<mpfr::mpreal>(const mpfr::mpreal& a, const mpfr::mpreal& b)
    110   {
    111     return a + (b-a) * random<mpfr::mpreal>();
    112   }
    113 
    114   inline bool isMuchSmallerThan(const mpfr::mpreal& a, const mpfr::mpreal& b, const mpfr::mpreal& eps)
    115   {
    116     return mpfr::abs(a) <= mpfr::abs(b) * eps;
    117   }
    118 
    119   inline bool isApprox(const mpfr::mpreal& a, const mpfr::mpreal& b, const mpfr::mpreal& eps)
    120   {
    121     return mpfr::isEqualFuzzy(a,b,eps);
    122   }
    123 
    124   inline bool isApproxOrLessThan(const mpfr::mpreal& a, const mpfr::mpreal& b, const mpfr::mpreal& eps)
    125   {
    126     return a <= b || mpfr::isEqualFuzzy(a,b,eps);
    127   }
    128 
    129   template<> inline long double cast<mpfr::mpreal,long double>(const mpfr::mpreal& x)
    130   { return x.toLDouble(); }
    131 
    132   template<> inline double cast<mpfr::mpreal,double>(const mpfr::mpreal& x)
    133   { return x.toDouble(); }
    134 
    135   template<> inline long cast<mpfr::mpreal,long>(const mpfr::mpreal& x)
    136   { return x.toLong(); }
    137 
    138   template<> inline int cast<mpfr::mpreal,int>(const mpfr::mpreal& x)
    139   { return int(x.toLong()); }
    140 
    141   // Specialize GEBP kernel and traits for mpreal (no need for peeling, nor complicated stuff)
    142   // This also permits to directly call mpfr's routines and avoid many temporaries produced by mpreal
    143     template<>
    144     class gebp_traits<mpfr::mpreal, mpfr::mpreal, false, false>
    145     {
    146     public:
    147       typedef mpfr::mpreal ResScalar;
    148       enum {
    149         Vectorizable = false,
    150         LhsPacketSize = 1,
    151         RhsPacketSize = 1,
    152         ResPacketSize = 1,
    153         NumberOfRegisters = 1,
    154         nr = 1,
    155         mr = 1,
    156         LhsProgress = 1,
    157         RhsProgress = 1
    158       };
    159       typedef ResScalar LhsPacket;
    160       typedef ResScalar RhsPacket;
    161       typedef ResScalar ResPacket;
    162       
    163     };
    164 
    165 
    166 
    167     template<typename Index, typename DataMapper, bool ConjugateLhs, bool ConjugateRhs>
    168     struct gebp_kernel<mpfr::mpreal,mpfr::mpreal,Index,DataMapper,1,1,ConjugateLhs,ConjugateRhs>
    169     {
    170       typedef mpfr::mpreal mpreal;
    171 
    172       EIGEN_DONT_INLINE
    173       void operator()(const DataMapper& res, const mpreal* blockA, const mpreal* blockB, 
    174                       Index rows, Index depth, Index cols, const mpreal& alpha,
    175                       Index strideA=-1, Index strideB=-1, Index offsetA=0, Index offsetB=0)
    176       {
    177         if(rows==0 || cols==0 || depth==0)
    178           return;
    179 
    180         mpreal  acc1(0,mpfr_get_prec(blockA[0].mpfr_srcptr())),
    181                 tmp (0,mpfr_get_prec(blockA[0].mpfr_srcptr()));
    182 
    183         if(strideA==-1) strideA = depth;
    184         if(strideB==-1) strideB = depth;
    185 
    186         for(Index i=0; i<rows; ++i)
    187         {
    188           for(Index j=0; j<cols; ++j)
    189           {
    190             const mpreal *A = blockA + i*strideA + offsetA;
    191             const mpreal *B = blockB + j*strideB + offsetB;
    192             
    193             acc1 = 0;
    194             for(Index k=0; k<depth; k++)
    195             {
    196               mpfr_mul(tmp.mpfr_ptr(), A[k].mpfr_srcptr(), B[k].mpfr_srcptr(), mpreal::get_default_rnd());
    197               mpfr_add(acc1.mpfr_ptr(), acc1.mpfr_ptr(), tmp.mpfr_ptr(),  mpreal::get_default_rnd());
    198             }
    199             
    200             mpfr_mul(acc1.mpfr_ptr(), acc1.mpfr_srcptr(), alpha.mpfr_srcptr(), mpreal::get_default_rnd());
    201             mpfr_add(res(i,j).mpfr_ptr(), res(i,j).mpfr_srcptr(), acc1.mpfr_srcptr(),  mpreal::get_default_rnd());
    202           }
    203         }
    204       }
    205     };
    206   } // end namespace internal
    207 }
    208 
    209 #endif // EIGEN_MPREALSUPPORT_MODULE_H
    210