Program Listing for File powerlaw_distribution.hpp

↰ Return to documentation for file (rcppsw/math/powerlaw_distribution.hpp)

#pragma once

/*******************************************************************************
 * Includes
 ******************************************************************************/
#include "rcppsw/math/rng.hpp"
#include "rcppsw/rcppsw.hpp"

/*******************************************************************************
 * Namespaces/Decls
 ******************************************************************************/
namespace rcppsw::math {

/*******************************************************************************
 * Class Definitions
 ******************************************************************************/
class powerlaw_distribution {
 public:
  powerlaw_distribution(size_t lb, size_t ub, size_t pwr)
      : m_lb(lb), m_ub(ub), m_pwr(pwr) {}
  virtual ~powerlaw_distribution(void) = default;

  double operator()(rng* rng) {
    double v = rng->uniform(0.0, 1.0);
    double pmax = std::pow(m_ub, m_pwr + 1);
    double pmin = std::pow(m_lb, m_pwr + 1);
    double tmp = pmin + (pmax - pmin) * v;
    return std::pow(tmp, 1.0 / (m_pwr + 1));
  }
  size_t pwr(void) const { return m_pwr; }
  size_t lb(void) const { return m_lb; }
  size_t ub(void) const { return m_ub; }

 private:
  /* clang-format off */
  size_t m_lb;
  size_t m_ub;
  size_t m_pwr;
  /* clang-format on */
};
} /* namespace rcppsw::math */