1 #ifndef STAN_MATH_PRIM_SCAL_PROB_INV_CHI_SQUARE_CCDF_LOG_HPP
2 #define STAN_MATH_PRIM_SCAL_PROB_INV_CHI_SQUARE_CCDF_LOG_HPP
4 #include <boost/random/chi_squared_distribution.hpp>
5 #include <boost/random/variate_generator.hpp>
31 template <
typename T_y,
typename T_dof>
32 typename return_type<T_y, T_dof>::type
41 static const char*
function(
"stan::math::inv_chi_square_ccdf_log");
47 using boost::math::tools::promote_args;
51 T_partials_return P(0.0);
58 "Degrees of freedom parameter", nu);
72 return operands_and_partials.
value(0.0);
84 T_partials_return, T_dof> gamma_vec(stan::length(nu));
86 T_partials_return, T_dof> digamma_vec(stan::length(nu));
90 const T_partials_return nu_dbl =
value_of(nu_vec[i]);
91 gamma_vec[i] =
tgamma(0.5 * nu_dbl);
92 digamma_vec[i] =
digamma(0.5 * nu_dbl);
97 for (
size_t n = 0; n < N; n++) {
100 if (
value_of(y_vec[n]) == std::numeric_limits<double>::infinity()) {
105 const T_partials_return y_dbl =
value_of(y_vec[n]);
106 const T_partials_return y_inv_dbl = 1.0 / y_dbl;
107 const T_partials_return nu_dbl =
value_of(nu_vec[n]);
110 const T_partials_return Pn = 1.0 -
gamma_q(0.5 * nu_dbl, 0.5
116 operands_and_partials.
d_x1[n] -= 0.5 * y_inv_dbl * y_inv_dbl
117 *
exp(-0.5*y_inv_dbl) *
pow(0.5*y_inv_dbl, 0.5*nu_dbl-1)
118 /
tgamma(0.5*nu_dbl) / Pn;
120 operands_and_partials.
d_x2[n]
124 digamma_vec[n]) / Pn;
127 return operands_and_partials.
value(P);
VectorView< T_return_type, false, true > d_x2
return_type< T_y, T_dof >::type inv_chi_square_ccdf_log(const T_y &y, const T_dof &nu)
bool check_not_nan(const char *function, const char *name, const T_y &y)
Return true if y is not NaN.
T value_of(const fvar< T > &v)
Return the value of the specified variable.
fvar< T > log(const fvar< T > &x)
T_return_type value(double value)
Returns a T_return_type with the value specified with the partial derivatves.
size_t length(const std::vector< T > &x)
T grad_reg_inc_gamma(T a, T z, T g, T dig, T precision=1e-6)
Metaprogram to determine if a type has a base scalar type that can be assigned to type double...
fvar< T > exp(const fvar< T > &x)
This class builds partial derivatives with respect to a set of operands.
size_t max_size(const T1 &x1, const T2 &x2)
VectorBuilder allocates type T1 values to be used as intermediate values.
bool check_consistent_sizes(const char *function, const char *name1, const T1 &x1, const char *name2, const T2 &x2)
Return true if the dimension of x1 is consistent with x2.
fvar< T > pow(const fvar< T > &x1, const fvar< T > &x2)
bool check_nonnegative(const char *function, const char *name, const T_y &y)
Return true if y is non-negative.
fvar< T > tgamma(const fvar< T > &x)
VectorView is a template expression that is constructed with a container or scalar, which it then allows to be used as an array using operator[].
boost::math::tools::promote_args< typename partials_type< typename scalar_type< T1 >::type >::type, typename partials_type< typename scalar_type< T2 >::type >::type, typename partials_type< typename scalar_type< T3 >::type >::type, typename partials_type< typename scalar_type< T4 >::type >::type, typename partials_type< typename scalar_type< T5 >::type >::type, typename partials_type< typename scalar_type< T6 >::type >::type >::type type
fvar< T > gamma_q(const fvar< T > &x1, const fvar< T > &x2)
bool check_positive_finite(const char *function, const char *name, const T_y &y)
Return true if y is positive and finite.
VectorView< T_return_type, false, true > d_x1
double negative_infinity()
Return negative infinity.
fvar< T > digamma(const fvar< T > &x)