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log_falling_factorial.hpp
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#ifndef STAN_MATH_FWD_SCAL_FUN_LOG_FALLING_FACTORIAL_HPP
#define STAN_MATH_FWD_SCAL_FUN_LOG_FALLING_FACTORIAL_HPP
#include <stan/math/fwd/core.hpp>
#include <stan/math/prim/scal/fun/log_falling_factorial.hpp>
#include <boost/math/special_functions/digamma.hpp>
namespace stan {
namespace math {
template<typename T>
inline fvar<T>
log_falling_factorial(const fvar<T>& x, const fvar<T>& n) {
using stan::math::log_falling_factorial;
using boost::math::digamma;
return fvar<T>(log_falling_factorial(x.val_, n.val_),
digamma(x.val_ + 1) * x.d_ - digamma(n.val_ + 1) * n.d_);
}
template<typename T>
inline fvar<T>
log_falling_factorial(const double x, const fvar<T>& n) {
using stan::math::log_falling_factorial;
using boost::math::digamma;
return fvar<T>(log_falling_factorial(x, n.val_),
-digamma(n.val_ + 1) * n.d_);
}
template<typename T>
inline fvar<T>
log_falling_factorial(const fvar<T>& x, const double n) {
using stan::math::log_falling_factorial;
using boost::math::digamma;
return fvar<T>(log_falling_factorial(x.val_, n),
digamma(x.val_ + 1) * x.d_);
}
}
}
#endif
core.hpp
stan::math::log_falling_factorial
fvar< T > log_falling_factorial(const fvar< T > &x, const fvar< T > &n)
Definition: log_falling_factorial.hpp:15
stan::math::fvar::d_
T d_
Definition: fvar.hpp:15
stan::math::fvar::val_
T val_
Definition: fvar.hpp:14
log_falling_factorial.hpp
stan::math::fvar
Definition: fvar.hpp:13
stan::math::digamma
fvar< T > digamma(const fvar< T > &x)
Definition: digamma.hpp:16

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