Array< double, 1, 3 > e(2,-3, 1./3.)
internal::enable_if< !(internal::is_same< typename Derived::Scalar, ScalarExponent >::value)&&EIGEN_SCALAR_BINARY_SUPPORTED(pow, typename Derived::Scalar, ScalarExponent), const EIGEN_EXPR_BINARYOP_SCALAR_RETURN_TYPE(Derived, ScalarExponent, pow) >::type pow(const Eigen::ArrayBase< Derived > &x, const ScalarExponent &exponent)