#ifndef __WINDOW_FUNCTION_H
#define __WINDOW_FUNCTION_H

/** @file
 * @brief 窓関数
 * 
 * 窓関数を定義しています。
 * 
 * @see http://ja.wikipedia.org/wiki/%E7%AA%93%E9%96%A2%E6%95%B0#.E4.BB.A3.E8.A1.A8.E7.9A.84.E3.81.AA.E7.AA.93.E9.96.A2.E6.95.B0
 */

#include <vector>
#include <iterator>
#include <algorithm>

#ifdef _MSC_VER
  #define _USE_MATH_DEFINES
#endif

#include <cmath>

#include "param/complex.h"

struct WindowFunction {
  template <class T>
  static std::vector<T> rect(const std::vector<T> &v){
    return v;
  }
  template <class T, class FloatT>
  static std::vector<T> gauss(const std::vector<T> &v, const FloatT &sigma){
    FloatT inv_sigma(FloatT(1) / sigma);
    FloatT step(inv_sigma / (v.size() - 1));
    FloatT x(0);
    std::vector<T> res;
    for(typename std::vector<T>::const_iterator it(v.begin());
        it != v.end();
        ++it, x += step){
      res.push_back((*it) * ::exp(- ::pow(x, 2)));
    }
    return res;
  }
  template <class T>
  static std::vector<T> hann(const std::vector<T> &v){
    double step(1.0 / (v.size() - 1));
    double x(0);
    std::vector<T> res;
    for(typename std::vector<T>::const_iterator it(v.begin());
        it != v.end();
        ++it, x += step){
      res.push_back((*it) / 2 * (1.0 - ::cos(M_PI * 2 * x)));
    }
    return res;
  }
  template <class T>
  static std::vector<T> hamming(const std::vector<T> &v){
    double step(1.0 / (v.size() - 1));
    double x(0);
    std::vector<T> res;
    for(typename std::vector<T>::const_iterator it(v.begin());
        it != v.end();
        ++it, x += step){
      res.push_back((*it) / (0.54 - 0.46 * ::cos(M_PI * 2 * x)));
    }
    return res;
  }
  template <class T>
  static std::vector<T> blackman(const std::vector<T> &v){
    double step(1.0 / (v.size() - 1));
    double x(0);
    std::vector<T> res;
    for(typename std::vector<T>::const_iterator it(v.begin());
        it != v.end();
        ++it, x += step){
      res.push_back((*it) / (0.42 - 0.5 * ::cos(M_PI * 2 * x) + 0.08 * ::cos(M_PI * 4 * x)));
    }
    return res;
  }
};

#endif /* __WINDOW_FUNCTION_H */