NumTools.h

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// SPDX-FileCopyrightText: The Bio++ Development Group
//
// SPDX-License-Identifier: CECILL-2.1

#ifndef BPP_NUMERIC_NUMTOOLS_H
#define BPP_NUMERIC_NUMTOOLS_H


#include "Function/Functions.h"

namespace bpp
{
// Forward declaration:
template<class Scalar> class RowMatrix;

class NumTools
{
public:
  template<class T> static T abs(T a) { return a < 0 ? -a : a; }

  template<class T> static T sign(T a) { return a < 0 ? -1 : (a == 0 ? 0 : 1); }

  template<class T> static T max(T a, T b) { return a > b ? a : b; }

  template<class T> static T min(T a, T b) { return a < b ? a : b; }

  template<class T> static T sign(T a, T b) { return abs<T>(a) * sign<T>(b); }

  template<class T> static T sqr(T a) { return a * a; }

  template<class T> static T logsum(T lnx, T lny)
  {
    return (lny < lnx) ?
           lnx + std::log(1. + exp(lny - lnx)) :
           lny + std::log(1. + exp(lnx - lny));
  }

  /**************************************************************************/

  template<class T> static void swap(T& a, T& b)
  {
    T swap = a;
    a = b;
    b = swap;
  }

  template<class T> static void shift(T& a, T& b, T c)
  {
    a = b; b = c;
  }

  template<class T> static void shift(T& a, T& b, T& c, T d)
  {
    a = b; b = c; c = d;
  }

  /**************************************************************************/

  template<class T> static T fact(T n) { return (n == 0) ? 1 : n* fact(n - 1); }

  /**************************************************************************/

  template<class T> static T logFact(T n) { return (n == 0) ? 0 : (std::log(n) + logFact(n - 1)); }

  /**************************************************************************/

  static double uniRoot(FunctionInterface& f, const std::string& param, double a, double b, double tolerance);

  /**************************************************************************/

  static std::unique_ptr<RowMatrix<double>> computeHessianMatrix(SecondOrderDerivable& function, const ParameterList& parameters);

  /**************************************************************************/
};
} // end of namespace bpp.
#endif // BPP_NUMERIC_NUMTOOLS_H