1 #ifndef STAN_MATH_REV_SCAL_FUN_GAMMA_P_HPP 2 #define STAN_MATH_REV_SCAL_FUN_GAMMA_P_HPP 14 class gamma_p_vv_vari :
public op_vv_vari {
16 gamma_p_vv_vari(vari* avi, vari* bvi) :
17 op_vv_vari(
gamma_p(avi->val_, bvi->val_),
23 if (
std::fabs(bvi_->val_ / avi_->val_) > 10 )
return;
25 double u =
gamma_p(avi_->val_, bvi_->val_);
30 double g =
tgamma(avi_->val_);
31 double dig =
digamma(avi_->val_);
34 double delta = s / (avi_->val_ * avi_->val_);
40 delta = s / ((k + avi_->val_) * (k + avi_->val_));
43 avi_->adj_ -= adj_ * ((u) * (dig - l)
45 bvi_->adj_ += adj_ * (
std::exp(-bvi_->val_)
46 *
std::pow(bvi_->val_, avi_->val_ - 1.0) / g);
50 class gamma_p_vd_vari :
public op_vd_vari {
52 gamma_p_vd_vari(vari* avi,
double b) :
53 op_vd_vari(
gamma_p(avi->val_, b),
62 double u =
gamma_p(avi_->val_, bd_);
67 double g =
tgamma(avi_->val_);
68 double dig =
digamma(avi_->val_);
71 double delta = s / (avi_->val_ * avi_->val_);
77 delta = s / ((k + avi_->val_) * (k + avi_->val_));
80 avi_->adj_ -= adj_ * ((u) * (dig - l)
85 class gamma_p_dv_vari :
public op_dv_vari {
87 gamma_p_dv_vari(
double a, vari* bvi) :
88 op_dv_vari(
gamma_p(a, bvi->val_),
105 return var(
new gamma_p_vv_vari(a.
vi_, b.
vi_));
110 return var(
new gamma_p_vd_vari(a.
vi_, b));
115 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)
Return the result of applying the gamma function to the specified argument.
fvar< T > digamma(const fvar< T > &x)
Return the derivative of the log gamma function at the specified argument.