DET.h

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////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2008-2021 The Octave Project Developers
//
// See the file COPYRIGHT.md in the top-level directory of this
// distribution or <https://octave.org/copyright/>.
//
// This file is part of Octave.
//
// Octave is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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////////////////////////////////////////////////////////////////////////
 
#if ! defined (octave_DET_h)
#define octave_DET_h 1
 
#include "octave-config.h"
 
#include <cmath>
 
#include "lo-mappers.h"
#include "oct-cmplx.h"
 
template <typename T>
class
base_det
{
public:
 
  base_det (T c = 1, int e = 0)
    : c2 (), e2 ()
  {
    c2 = octave::math::log2 (c, e2);
    e2 += e;
  }
 
  base_det (T c, double e, double b)
    : c2 (), e2 ()
  {
    e *= octave::math::log2 (b);
    e2 = e;
    c *= octave::math::exp2 (e - e2);
    int f;
    c2 = octave::math::log2 (c, f);
    e2 += f;
  }
 
  base_det (const base_det& a) : c2 (a.c2), e2 (a.e2) { }
 
  base_det& operator = (const base_det& a)
  {
    c2 = a.c2;
    e2 = a.e2;
    return *this;
  }
 
  T coef (void) const { return c2; }
  int exp (void) const { return e2; }
 
  T value () const { return c2 * static_cast<T> (std::ldexp (1.0, e2)); }
  operator T () const { return value (); }
 
  base_det square () const { return base_det (c2*c2, e2+e2); }
 
  void operator *= (T t)
  {
    int e;
    c2 *= t;
    // Renormalize c2 to [0.5, 1), and find required change in exponent.
    c2 = octave::math::log2 (c2, e);
    e2 += e;
  }
 
private:
 
  T c2;
  int e2;
};
 
// Provide the old types by typedefs.
typedef base_det<double> DET;
typedef base_det<float> FloatDET;
typedef base_det<Complex> ComplexDET;
typedef base_det<FloatComplex> FloatComplexDET;
 
#endif