  Aiming at applications to the scientific visualization of three dimensional
simulations with time evolution, a keyboard based control method to specify
rotations in four dimensions is proposed. It is known that four dimensional
rotations are generally so-called double rotations, and a double rotation is a
combination of simultaneously applied two simple rotations. The proposed method
can specify both the simple and double rotations by single key typings of the
keyboard. The method is tested in visualizations of a regular pentachoron in
four dimensional space by a hyperplane slicing.
