lmgamma.hpp

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#ifndef STAN_MATH_FWD_FUN_LMGAMMA_HPP
#define STAN_MATH_FWD_FUN_LMGAMMA_HPP
 
#include <stan/math/fwd/meta.hpp>
#include <stan/math/fwd/core.hpp>
#include <stan/math/fwd/fun/digamma.hpp>
#include <stan/math/prim/fun/lmgamma.hpp>
#include <cmath>
 
namespace stan {
namespace math {
 
template <typename T>
inline fvar<return_type_t<T, int>> lmgamma(int x1, const fvar<T>& x2) {
  T deriv = 0;
  for (int count = 1; count < x1 + 1; count++) {
    deriv += x2.d_ * digamma(x2.val_ + (1.0 - count) / 2.0);
  }
  return fvar<return_type_t<T, int>>(lmgamma(x1, x2.val_), deriv);
}
}  // namespace math
}  // namespace stan
#endif