1 #ifndef STAN_MATH_FWD_SCAL_FUN_LOG1M_INV_LOGIT_HPP 2 #define STAN_MATH_FWD_SCAL_FUN_LOG1M_INV_LOGIT_HPP 3 4 #include <stan/math/fwd/core.hpp> 5 #include <stan/math/prim/scal/fun/log1m_inv_logit.hpp> 6 #include <cmath> 7 8 namespace stan { 9 namespace math { 10 11 /** 12 * Return the natural logarithm of one minus the inverse logit of 13 * the specified argument. 14 * 15 * @tparam T scalar type of forward-mode autodiff variable 16 * argument. 17 * @param x argument 18 * @return log of one minus the inverse logit of the argument 19 */ 20 template <typename T> log1m_inv_logit(const fvar<T> & x)21inline fvar<T> log1m_inv_logit(const fvar<T>& x) { 22 using std::exp; 23 return fvar<T>(log1m_inv_logit(x.val_), -x.d_ / (1 + exp(-x.val_))); 24 } 25 26 } // namespace math 27 } // namespace stan 28 #endif 29