text: #ifndef STAN_MATH_REV_SCAL_FUN_LOG_RISING_FACTORIAL_HPP
  #define STAN_MATH_REV_SCAL_FUN_LOG_RISING_FACTORIAL_HPP
  
  #include <stan/math/rev/core.hpp>
  #include <stan/math/prim/scal/fun/log_rising_factorial.hpp>
  #include <stan/math/prim/scal/fun/digamma.hpp>
  #include <stan/math/rev/scal/fun/digamma.hpp>
  
  namespace stan {
    namespace math {
  
      namespace {
  
        class log_rising_factorial_vv_vari : public op_vv_vari {
        public:
          log_rising_factorial_vv_vari(vari* avi, vari* bvi) :
            op_vv_vari(log_rising_factorial(avi->val_, bvi->val_),
                       avi, bvi) {
          }
          void chain() {
            avi_->adj_ += adj_ * (digamma(avi_->val_ + bvi_->val_)
                                  - digamma(avi_->val_));
            bvi_->adj_ += adj_ * digamma(avi_->val_ + bvi_->val_);
          }
        };
  
        class log_rising_factorial_vd_vari : public op_vd_vari {
        public:
          log_rising_factorial_vd_vari(vari* avi, double b) :
            op_vd_vari(log_rising_factorial(avi->val_, b), avi, b) {
          }
          void chain() {
            avi_->adj_ += adj_ * (digamma(avi_->val_ + bd_)
                                  - digamma(avi_->val_));
          }
        };
  
        class log_rising_factorial_dv_vari : public op_dv_vari {
        public:
          log_rising_factorial_dv_vari(double a, vari* bvi) :
            op_dv_vari(log_rising_factorial(a, bvi->val_), a, bvi) {
          }
          void chain() {
            bvi_->adj_ += adj_ * digamma(bvi_->val_ + ad_);
          }
        };
      }
  
      inline var log_rising_factorial(const var& a,
                                      double b) {
        return var(new log_rising_factorial_vd_vari(a.vi_, b));
      }
  
      inline var log_rising_factorial(const var& a,
                                      const var& b) {
        return var(new log_rising_factorial_vv_vari(a.vi_, b.vi_));
      }
  
      inline var log_rising_factorial(double a,
                                      const var& b) {
        return var(new log_rising_factorial_dv_vari(a, b.vi_));
      }
  
    }
  }
  #endif
  