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digamma.hpp
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1 #ifndef STAN_MATH_REV_SCAL_FUN_DIGAMMA_HPP
2 #define STAN_MATH_REV_SCAL_FUN_DIGAMMA_HPP
3
4 #include <boost/math/special_functions/zeta.hpp>
5 #include <stan/math/rev/core.hpp>
6 #include <stan/math/prim/scal/fun/trigamma.hpp>
7 #include <stan/math/prim/scal/fun/digamma.hpp>
8
9 namespace stan {
10 namespace math {
11
12 namespace {
13 class digamma_vari : public op_v_vari {
14 public:
15 explicit digamma_vari(vari* avi) :
16 op_v_vari(digamma(avi->val_), avi) {
17 }
18 void chain() {
19 avi_->adj_ += adj_ * trigamma(avi_->val_);
20 }
21 };
22 }
23
24 inline var digamma(const stan::math::var& a) {
25 return var(new digamma_vari(a.vi_));
26 }
27
28 }
29 }
30 #endif
stan::math::trigamma
T trigamma(T x)
Definition: trigamma.hpp:50
core.hpp
stan
Definition: log_sum_exp.hpp:8
digamma.hpp
stan::math::var
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:31
stan::math::var::vi_
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:43
trigamma.hpp
stan::math::digamma
fvar< T > digamma(const fvar< T > &x)
Definition: digamma.hpp:16

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