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log_rising_factorial.hpp
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1 #ifndef STAN_MATH_REV_SCAL_FUN_LOG_RISING_FACTORIAL_HPP
2 #define STAN_MATH_REV_SCAL_FUN_LOG_RISING_FACTORIAL_HPP
3 
4 #include <stan/math/rev/core.hpp>
8 
9 namespace stan {
10  namespace math {
11 
12  namespace {
13 
14  class log_rising_factorial_vv_vari : public op_vv_vari {
15  public:
16  log_rising_factorial_vv_vari(vari* avi, vari* bvi) :
17  op_vv_vari(stan::math::log_rising_factorial(avi->val_, bvi->val_),
18  avi, bvi) {
19  }
20  void chain() {
21  avi_->adj_ += adj_ * (digamma(avi_->val_ + bvi_->val_)
22  - digamma(avi_->val_));
23  bvi_->adj_ += adj_ * digamma(avi_->val_ + bvi_->val_);
24  }
25  };
26 
27  class log_rising_factorial_vd_vari : public op_vd_vari {
28  public:
29  log_rising_factorial_vd_vari(vari* avi, double b) :
30  op_vd_vari(stan::math::log_rising_factorial(avi->val_, b), avi, b) {
31  }
32  void chain() {
33  avi_->adj_ += adj_ * (digamma(avi_->val_ + bd_)
34  - digamma(avi_->val_));
35  }
36  };
37 
38  class log_rising_factorial_dv_vari : public op_dv_vari {
39  public:
40  log_rising_factorial_dv_vari(double a, vari* bvi) :
41  op_dv_vari(stan::math::log_rising_factorial(a, bvi->val_), a, bvi) {
42  }
43  void chain() {
44  bvi_->adj_ += adj_ * digamma(bvi_->val_ + ad_);
45  }
46  };
47  }
48 
49  inline var log_rising_factorial(const var& a,
50  const double& b) {
51  return var(new log_rising_factorial_vd_vari(a.vi_, b));
52  }
53 
54  inline var log_rising_factorial(const var& a,
55  const var& b) {
56  return var(new log_rising_factorial_vv_vari(a.vi_, b.vi_));
57  }
58 
59  inline var log_rising_factorial(const double& a,
60  const var& b) {
61  return var(new log_rising_factorial_dv_vari(a, b.vi_));
62  }
63  }
64 }
65 #endif
Independent (input) and dependent (output) variables for gradients.
Definition: var.hpp:32
vari * vi_
Pointer to the implementation of this variable.
Definition: var.hpp:44
fvar< T > log_rising_factorial(const fvar< T > &x, const fvar< T > &n)
fvar< T > digamma(const fvar< T > &x)
Definition: digamma.hpp:16

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