1 #ifndef STAN_MATH_FWD_SCAL_FUN_SQRT_HPP 2 #define STAN_MATH_FWD_SCAL_FUN_SQRT_HPP 3 4 #include <stan/math/fwd/core.hpp> 5 6 #include <stan/math/prim/scal/fun/inv_sqrt.hpp> 7 8 namespace stan { 9 namespace math { 10 11 template <typename T> sqrt(const fvar<T> & x)12inline fvar<T> sqrt(const fvar<T>& x) { 13 using std::sqrt; 14 return fvar<T>(sqrt(x.val_), 0.5 * x.d_ * inv_sqrt(x.val_)); 15 } 16 } // namespace math 17 } // namespace stan 18 #endif 19