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kpeter (Peter Kovacs)
Support real types + numerical stability fix in NS (#254) - Real types are supported by appropriate inicialization. - A feature of the XTI spanning tree structure is removed to ensure numerical stability (could cause problems using integer types). The node potentials are updated always on the lower subtree, in order to prevent overflow problems. The former method isn't notably faster during to our tests.
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/* -*- mode: C++; indent-tabs-mode: nil; -*-

 *

 * This file is a part of LEMON, a generic C++ optimization library.

 *

 * Copyright (C) 2003-2009

 * Egervary Jeno Kombinatorikus Optimalizalasi Kutatocsoport

 * (Egervary Research Group on Combinatorial Optimization, EGRES).

 *

 * Permission to use, modify and distribute this software is granted

 * provided that this copyright notice appears in all copies. For

 * precise terms see the accompanying LICENSE file.

 *

 * This software is provided "AS IS" with no warranty of any kind,

 * express or implied, and with no claim as to its suitability for any

 * purpose.

 *

 */



#ifndef LEMON_MATH_H

#define LEMON_MATH_H



///\ingroup misc

///\file

///\brief Some extensions to the standard \c cmath library.

///

///Some extensions to the standard \c cmath library.

///

///This file includes the standard math library (cmath).



#include<cmath>



namespace lemon {



  /// \addtogroup misc

  /// @{



  /// The Euler constant

  const long double E       = 2.7182818284590452353602874713526625L;

  /// log_2(e)

  const long double LOG2E   = 1.4426950408889634073599246810018921L;

  /// log_10(e)

  const long double LOG10E  = 0.4342944819032518276511289189166051L;

  /// ln(2)

  const long double LN2     = 0.6931471805599453094172321214581766L;

  /// ln(10)

  const long double LN10    = 2.3025850929940456840179914546843642L;

  /// pi

  const long double PI      = 3.1415926535897932384626433832795029L;

  /// pi/2

  const long double PI_2    = 1.5707963267948966192313216916397514L;

  /// pi/4

  const long double PI_4    = 0.7853981633974483096156608458198757L;

  /// sqrt(2)

  const long double SQRT2   = 1.4142135623730950488016887242096981L;

  /// 1/sqrt(2)

  const long double SQRT1_2 = 0.7071067811865475244008443621048490L;



  ///Check whether the parameter is NaN or not

  

  ///This function checks whether the parameter is NaN or not.

  ///Is should be equivalent with std::isnan(), but it is not

  ///provided by all compilers.

  inline bool isNaN(double v)

    {

      return v!=v;

    }



  /// @}



} //namespace lemon



#endif //LEMON_TOLERANCE_H