densitytreeleaf.cpp

dysii是一款非常出色的滤波函数库

#include "DensityTreeLeaf.hpp"

#include "Random.hpp"

using namespace indii::ml::aux;

DensityTreeLeaf::DensityTreeLeaf() {
  //
}

DensityTreeLeaf::DensityTreeLeaf(const vector& lower, const vector& upper,
    const double weight, const double volume) :
    DensityTreeNode(lower, upper, weight, volume) {
  //
}

DensityTreeLeaf::~DensityTreeLeaf() {
  //
}

vector DensityTreeLeaf::sumExpectation() {
  return getWeight() * (getLower() + getUpper()) / 2.0;
}

symmetric_matrix DensityTreeLeaf::sumCovariance() {
  vector diff(getUpper() - getLower());
  vector mu((getLower() + getUpper()) / 2.0);
  
  return getWeight() * (outer_prod(diff, diff) / 12.0  + outer_prod(mu, mu));
}

vector DensityTreeLeaf::sample(const double u) {
  /* pre-condition */
  assert (u >= 0.0 && u <= getWeight());

  const vector& lower = getLower();
  const vector& upper = getUpper();
  const unsigned int N = lower.size();
  vector s(N);
  unsigned int i;
  
  for (i = 0; i < N; i++) {
    s(i) = Random::uniform(lower(i), upper(i));
  }

  return s;
}

double DensityTreeLeaf::densityAt(const vector& x) {
  /* pre-condition */
  assert (x.size() == getLower().size());

  return getDensity();
}