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lbeta.hpp
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1 #ifndef STAN_MATH_FWD_SCAL_FUN_LBETA_HPP
2 #define STAN_MATH_FWD_SCAL_FUN_LBETA_HPP
3
4 #include <stan/math/fwd/core.hpp>
5
6 #include <boost/math/special_functions/digamma.hpp>
7 #include <stan/math/prim/scal/fun/lbeta.hpp>
8
9 namespace stan {
10 namespace math {
11
12 template <typename T>
13 inline
14 fvar<T>
15 lbeta(const fvar<T>& x1, const fvar<T>& x2) {
16 using boost::math::digamma;
17 return fvar<T>(lbeta(x1.val_, x2.val_),
18 x1.d_ * digamma(x1.val_)
19 + x2.d_ * digamma(x2.val_)
20 - (x1.d_ + x2.d_) * digamma(x1.val_ + x2.val_));
21 }
22
23 template <typename T>
24 inline
25 fvar<T>
26 lbeta(const double x1, const fvar<T>& x2) {
27 using boost::math::digamma;
28 return fvar<T>(lbeta(x1, x2.val_),
29 x2.d_ * digamma(x2.val_) - x2.d_ * digamma(x1 + x2.val_));
30 }
31
32 template <typename T>
33 inline
34 fvar<T>
35 lbeta(const fvar<T>& x1, const double x2) {
36 using boost::math::digamma;
37 return fvar<T>(lbeta(x1.val_, x2),
38 x1.d_ * digamma(x1.val_) - x1.d_ * digamma(x1.val_ + x2));
39 }
40 }
41 }
42 #endif
core.hpp
stan::math::fvar::d_
T d_
Definition: fvar.hpp:14
stan
Definition: log_sum_exp.hpp:8
stan::math::lbeta
fvar< T > lbeta(const fvar< T > &x1, const fvar< T > &x2)
Definition: lbeta.hpp:15
stan::math::fvar::val_
T val_
Definition: fvar.hpp:13
lbeta.hpp
stan::math::fvar
Definition: fvar.hpp:12
stan::math::digamma
fvar< T > digamma(const fvar< T > &x)
Definition: digamma.hpp:15

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