sqrt.hpp

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#ifndef STAN_MATH_FWD_FUN_SQRT_HPP
#define STAN_MATH_FWD_FUN_SQRT_HPP
 
#include <stan/math/fwd/meta.hpp>
#include <stan/math/fwd/core.hpp>
#include <stan/math/prim/fun/inv_sqrt.hpp>
#include <stan/math/prim/fun/sqrt.hpp>
#include <stan/math/fwd/fun/inv_sqrt.hpp>
#include <stan/math/fwd/fun/sqrt.hpp>
#include <cmath>
#include <complex>
 
namespace stan {
namespace math {
 
template <typename T>
inline fvar<T> sqrt(const fvar<T>& x) {
  using std::sqrt;
  if (value_of_rec(x.val_) == 0.0) {
    return fvar<T>(sqrt(x.val_), 0.0 * x.d_);
  }
  return fvar<T>(sqrt(x.val_), 0.5 * x.d_ * inv_sqrt(x.val_));
}
 
template <typename T>
inline std::complex<fvar<T>> sqrt(const std::complex<fvar<T>>& z) {
  return internal::complex_sqrt(z);
}
 
}  // namespace math
}  // namespace stan
#endif