/// <summary>四元数純第4成分</summary>
        public static Tensor QuaternionPureK(Tensor X)
        {
            Function function = new Functions.Quaternion.QuaternionPureK();

            Shape y_shape = function.OutputShapes(X.Shape)[0];

            Tensor y = new Tensor(y_shape);

            function.Execute(new Tensor[] { X }, new Tensor[] { y });

            return(y);
        }
        /// <summary>四元数純第4成分</summary>
        public static VariableNode QuaternionPureK(VariableNode X)
        {
            Function function = new Functions.Quaternion.QuaternionPureK();

            return(Apply(function, X)[0]);
        }