1 #ifndef STAN_MATH_REV_SCAL_FUN_GAMMA_P_HPP
2 #define STAN_MATH_REV_SCAL_FUN_GAMMA_P_HPP
6 #include <boost/math/special_functions/gamma.hpp>
7 #include <boost/math/special_functions/digamma.hpp>
14 class gamma_p_vv_vari :
public op_vv_vari {
16 gamma_p_vv_vari(vari* avi, vari* bvi) :
17 op_vv_vari(stan::math::
gamma_p(avi->val_, bvi->val_),
23 if (
std::fabs(bvi_->val_ / avi_->val_) > 10 )
return;
34 double delta = s / (avi_->val_ * avi_->val_);
40 delta = s / ((k + avi_->val_) * (k + avi_->val_));
44 avi_->adj_ -= adj_ * ((u) * (dig - l)
46 bvi_->adj_ += adj_ * (
std::exp(-bvi_->val_)
47 *
std::pow(bvi_->val_, avi_->val_ - 1.0) / g);
51 class gamma_p_vd_vari :
public op_vd_vari {
53 gamma_p_vd_vari(vari* avi,
double b) :
54 op_vd_vari(stan::math::
gamma_p(avi->val_, b),
72 double delta = s / (avi_->val_ * avi_->val_);
78 delta = s / ((k + avi_->val_) * (k + avi_->val_));
81 avi_->adj_ -= adj_ * ((u) * (dig - l)
86 class gamma_p_dv_vari :
public op_dv_vari {
88 gamma_p_dv_vari(
double a, vari* bvi) :
89 op_dv_vari(stan::math::
gamma_p(a, bvi->val_),
106 return var(
new gamma_p_vv_vari(a.
vi_, b.
vi_));
111 return var(
new gamma_p_vd_vari(a.
vi_, b));
116 return var(
new gamma_p_dv_vari(a, b.
vi_));
fvar< T > fabs(const fvar< T > &x)
fvar< T > log(const fvar< T > &x)
Independent (input) and dependent (output) variables for gradients.
fvar< T > exp(const fvar< T > &x)
vari * vi_
Pointer to the implementation of this variable.
fvar< T > gamma_p(const fvar< T > &x1, const fvar< T > &x2)
double e()
Return the base of the natural logarithm.
fvar< T > pow(const fvar< T > &x1, const fvar< T > &x2)
fvar< T > tgamma(const fvar< T > &x)
fvar< T > digamma(const fvar< T > &x)