Stan Math Library  2.20.0
reverse mode automatic differentiation
tgamma.hpp
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1 #ifndef STAN_MATH_FWD_SCAL_FUN_TGAMMA_HPP
2 #define STAN_MATH_FWD_SCAL_FUN_TGAMMA_HPP
3 
4 #include <stan/math/fwd/meta.hpp>
5 #include <stan/math/fwd/core.hpp>
7 #include <boost/math/special_functions/digamma.hpp>
8 
9 namespace stan {
10 namespace math {
11 
20 template <typename T>
21 inline fvar<T> tgamma(const fvar<T>& x) {
23  T u = tgamma(x.val_);
24  return fvar<T>(u, x.d_ * u * digamma(x.val_));
25 }
26 } // namespace math
27 } // namespace stan
28 #endif
T d_
The tangent (derivative) of this variable.
Definition: fvar.hpp:50
T val_
The value of this variable.
Definition: fvar.hpp:45
fvar< T > tgamma(const fvar< T > &x)
Return the result of applying the gamma function to the specified argument.
Definition: tgamma.hpp:21
This template class represents scalars used in forward-mode automatic differentiation, which consist of values and directional derivatives of the specified template type.
Definition: fvar.hpp:41
fvar< T > digamma(const fvar< T > &x)
Return the derivative of the log gamma function at the specified argument.
Definition: digamma.hpp:23

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