Dirichlet_inl.h

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namespace gum {

  // default constructor
  INLINE Dirichlet::Dirichlet(const param_type& params, unsigned int seed) :
      __generator(gum::getRandomGenerator(seed)), __params(params) {
    GUM_CONSTRUCTOR(Dirichlet);
  }

  // copy constructor
  INLINE Dirichlet::Dirichlet(const Dirichlet& from) :
      __generator(from.__generator), __gamma(from.__gamma),
      __params(from.__params) {
    GUM_CONS_CPY(Dirichlet);
  }

  // move constructor
  INLINE Dirichlet::Dirichlet(Dirichlet&& from) :
      __generator(std::move(from.__generator)), __gamma(std::move(from.__gamma)),
      __params(std::move(from.__params)) {
    GUM_CONS_MOV(Dirichlet);
  }

  // destructor
  INLINE Dirichlet::~Dirichlet() { GUM_DESTRUCTOR(Dirichlet); }

  // copy operator
  INLINE Dirichlet& Dirichlet::operator=(const Dirichlet& from) {
    if (&from != this) {
      __generator = from.__generator;
      __gamma = from.__gamma;
      __params = from.__params;
    }
    return *this;
  }

  // move operator
  INLINE Dirichlet& Dirichlet::operator=(Dirichlet&& from) {
    if (&from != this) {
      __generator = std::move(from.__generator);
      __gamma = std::move(from.__gamma);
      __params = std::move(from.__params);
    }
    return *this;
  }

  // returns a sample from the Dirichlet distribution
  INLINE Dirichlet::result_type Dirichlet::operator()() {
    Size        size = Size(__params.size());
    result_type res(size);
    float       sum = 0.0f;
    while (sum == 0.0f) {
      for (Idx i = 0; i < size; ++i) {
        __gamma.param(
           std::gamma_distribution< float >::param_type(__params[i], 1));
        res[i] = __gamma(__generator);
        sum += res[i];
      }
    }
    for (Idx i = 0; i < size; ++i) {
      res[i] /= sum;
    }
    return res;
  }

  // returns a sample from the Dirichlet distribution
  INLINE Dirichlet::result_type Dirichlet::
                                operator()(const Dirichlet::param_type& parm) {
    Size        size = Size(parm.size());
    result_type res(size);
    float       sum = 0.0f;
    while (sum == 0.0f) {
      for (Idx i = 0; i < size; ++i) {
        __gamma.param(std::gamma_distribution< float >::param_type(parm[i], 1));
        res[i] = __gamma(__generator);
        sum += res[i];
      }
    }
    for (Idx i = 0; i < size; ++i) {
      res[i] /= sum;
    }
    return res;
  }

  // returns the parameters of the distribution
  INLINE const Dirichlet::param_type& Dirichlet::param() const noexcept {
    return __params;
  }

  // sets the parameters of the distribution
  INLINE void Dirichlet::param(const Dirichlet::param_type& parm) {
    __params = parm;
  }

  // Returns the greatest lower bound of the range of values possibly returned
  INLINE float Dirichlet::min() const noexcept { return 0.0f; }

  // Returns the lowest higher bound of the range of values possibly returned
  INLINE float Dirichlet::max() const noexcept { return 1.0f; }

} /* namespace gum */