constants.hpp

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#ifndef STAN_MATH_PRIM_FUN_CONSTANTS_HPP
#define STAN_MATH_PRIM_FUN_CONSTANTS_HPP
 
#include <stan/math/prim/meta.hpp>
#include <stan/math/prim/fun/inv.hpp>
#include <boost/math/constants/constants.hpp>
#include <cmath>
#include <limits>
 
namespace stan {
namespace math {
 
// TODO(anyone) Use constexpr when moving to C++17
 
static constexpr double e() { return boost::math::constants::e<double>(); }
 
static constexpr double egamma() {
  return boost::math::constants::euler<double>();
}
 
static constexpr double pi() { return boost::math::constants::pi<double>(); }
 
static constexpr double EPSILON = std::numeric_limits<double>::epsilon();
 
static constexpr double INFTY = std::numeric_limits<double>::infinity();
 
static constexpr double NEGATIVE_INFTY = -INFTY;
 
static constexpr double NOT_A_NUMBER = std::numeric_limits<double>::quiet_NaN();
 
static constexpr double TWO_PI = boost::math::constants::two_pi<double>();
 
static constexpr double LOG_ZERO = -INFTY;
 
const double LOG_EPSILON = std::log(EPSILON);
 
static constexpr double LOG_TWO = boost::math::constants::ln_two<double>();
 
static constexpr double LOG_PI = 1.14472988584940017414342735135;
 
static constexpr double LOG_HALF = -LOG_TWO;
 
static constexpr double LOG_TWO_PI = LOG_TWO + LOG_PI;
 
static constexpr double LOG_PI_OVER_FOUR = 0.25 * LOG_PI;
 
static constexpr double LOG_SQRT_PI = LOG_PI / 2;
 
static constexpr double LOG_TEN = boost::math::constants::ln_ten<double>();
 
static constexpr double SQRT_TWO = boost::math::constants::root_two<double>();
 
static constexpr double SQRT_PI = boost::math::constants::root_pi<double>();
 
static constexpr double SQRT_TWO_PI
    = boost::math::constants::root_two_pi<double>();
 
static constexpr double SQRT_TWO_OVER_SQRT_PI = SQRT_TWO / SQRT_PI;
 
static constexpr double INV_SQRT_TWO
    = boost::math::constants::one_div_root_two<double>();
 
static constexpr double INV_SQRT_PI
    = boost::math::constants::one_div_root_pi<double>();
 
static constexpr double INV_SQRT_TWO_PI
    = boost::math::constants::one_div_root_two_pi<double>();
 
static constexpr double TWO_OVER_SQRT_PI
    = boost::math::constants::two_div_root_pi<double>();
 
static constexpr double HALF_LOG_TWO = 0.5 * LOG_TWO;
 
static constexpr double HALF_LOG_TWO_PI = 0.5 * LOG_TWO_PI;
 
const double NEG_LOG_SQRT_TWO_PI = -std::log(SQRT_TWO_PI);
 
const double POISSON_MAX_RATE = std::pow(2.0, 30);
 
static constexpr inline double positive_infinity() { return INFTY; }
 
static constexpr inline double negative_infinity() { return NEGATIVE_INFTY; }
 
static constexpr inline double not_a_number() { return NOT_A_NUMBER; }
 
static constexpr inline double machine_precision() { return EPSILON; }
 
static constexpr inline double log10() { return LOG_TEN; }
 
static constexpr inline double sqrt2() { return SQRT_TWO; }
 
}  // namespace math
}  // namespace stan
 
#endif