source: src/Potentials/helpers.hpp@ 5c78e3

/*
 * helpers.hpp
 *
 *  Created on: Sep 26, 2012
 *      Author: heber
 */

#ifndef POTENTIALS_HELPERS_HPP_
#define POTENTIALS_HELPERS_HPP_


// include config.h
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <cmath>
//#include <iomanip>
#include <limits>
//#include <sstream>

#include "FunctionApproximation/FunctionModel.hpp"
#include "FunctionApproximation/FunctionArgument.hpp"

//#include "CodePatterns/Log.hpp"

namespace Helpers
{

  /** Integer-optimized version for power of n.
   *
   * This is taken from Julian Iseringhausen's VMG project which is under
   * GPL.
   *
   * @param base base
   * @param power power to take \a base to
   * @return \a base to the power of \a power
   */
  inline int intpow(int base, unsigned int power)
  {
    int result = 1;
    while (power != 0) {
      if (power & 1)
        result *= base;
      base *= base;
      power >>= 1;
    }
    return result;
  }

  /** Double-optimized version for power of n.
   *
   * This is taken from Julian Iseringhausen's VMG project which is under
   * GPL.
   *
   * @param base base
   * @param power power to take \a base to
   * @return \a base to the power of \a power
   */
  inline double pow(double base, unsigned int power)
  {
    double result = 1.0;
    while (power != 0) {
      if (power & 1)
        result *= base;
      base *= base;
      power >>= 1;
    }
    return result;
  }

  /** Equality operator that takes numerical precision into account.
   *
   * \param first first operand
   * \param second second operand
   * \param factor factor to influence numeric threshold
   */
  template <typename T>
  inline bool isEqual(const T &first, const T &second, const double factor=1.) {
//    std::stringstream stream;
//    stream << std::setprecision(10)
//    << "Comparing " << first << " to " << second << ": "
//    << fabs(first-second) << "<" << std::numeric_limits<T>::epsilon()*factor << "?";
//    LOG(1, stream.str());
    return (fabs(first-second) < std::numeric_limits<T>::epsilon()*factor);
  }

  inline std::vector< FunctionModel::arguments_t >
  NoOp_Triplefunction(
      const argument_t &,
      const double)
  {
    return std::vector< FunctionModel::arguments_t >();
  }

  inline FunctionModel::arguments_t
  NoOp_Filterfunction(
      const FunctionModel::arguments_t &args
      )
  {
    return args;
  }

  inline FunctionModel::arguments_t
  returnEmptyArguments()
  {
    return FunctionModel::arguments_t();
  }

}; /* namespace Helpers */


#endif /* POTENTIALS_HELPERS_HPP_ */