inline RealType kurtosis_excess(const gamma_distribution<RealType, Policy>& dist)
{
BOOST_MATH_STD_USING // for ADL of std functions
static const char* function = "lslboost::math::kurtosis_excess(const gamma_distribution<%1%>&)";
RealType shape = dist.shape();
RealType scale = dist.scale();
RealType result = 0;
if(false == detail::check_gamma(function, scale, shape, &result, Policy()))
return result;
result = 6 / shape;
return result;
}
inline RealType variance(const gamma_distribution<RealType, Policy>& dist)
{
BOOST_MATH_STD_USING // for ADL of std functions
static const char* function = "boost::math::variance(const gamma_distribution<%1%>&)";
RealType shape = dist.shape();
RealType scale = dist.scale();
RealType result;
if(false == detail::check_gamma(function, scale, shape, &result, Policy()))
return result;
result = shape * scale * scale;
return result;
}
inline RealType cdf(const gamma_distribution<RealType, Policy>& dist, const RealType& x)
{
BOOST_MATH_STD_USING // for ADL of std functions
static const char* function = "lslboost::math::cdf(const gamma_distribution<%1%>&, %1%)";
RealType shape = dist.shape();
RealType scale = dist.scale();
RealType result = 0;
if(false == detail::check_gamma(function, scale, shape, &result, Policy()))
return result;
if(false == detail::check_gamma_x(function, x, &result, Policy()))
return result;
result = lslboost::math::gamma_p(shape, x / scale, Policy());
return result;
} // cdf
inline RealType mode(const gamma_distribution<RealType, Policy>& dist)
{
BOOST_MATH_STD_USING // for ADL of std functions
static const char* function = "lslboost::math::mode(const gamma_distribution<%1%>&)";
RealType shape = dist.shape();
RealType scale = dist.scale();
RealType result = 0;
if(false == detail::check_gamma(function, scale, shape, &result, Policy()))
return result;
if(shape < 1)
return policies::raise_domain_error<RealType>(
function,
"The mode of the gamma distribution is only defined for values of the shape parameter >= 1, but got %1%.",
shape, Policy());
result = (shape - 1) * scale;
return result;
}
inline RealType quantile(const gamma_distribution<RealType, Policy>& dist, const RealType& p)
{
BOOST_MATH_STD_USING // for ADL of std functions
static const char* function = "lslboost::math::quantile(const gamma_distribution<%1%>&, %1%)";
RealType shape = dist.shape();
RealType scale = dist.scale();
RealType result = 0;
if(false == detail::check_gamma(function, scale, shape, &result, Policy()))
return result;
if(false == detail::check_probability(function, p, &result, Policy()))
return result;
if(p == 1)
return policies::raise_overflow_error<RealType>(function, 0, Policy());
result = gamma_p_inv(shape, p, Policy()) * scale;
return result;
}
inline RealType pdf(const gamma_distribution<RealType, Policy>& dist, const RealType& x)
{
BOOST_MATH_STD_USING // for ADL of std functions
static const char* function = "boost::math::pdf(const gamma_distribution<%1%>&, %1%)";
RealType shape = dist.shape();
RealType scale = dist.scale();
RealType result;
if(false == detail::check_gamma(function, scale, shape, &result, Policy()))
return result;
if(false == detail::check_gamma_x(function, x, &result, Policy()))
return result;
if(x == 0)
{
return 0;
}
result = gamma_p_derivative(shape, x / scale, Policy()) / scale;
return result;
} // pdf