PenCalc: a novel application of on-line mathematical expression recognition technology

Most of the calculator programs found in existing pen-based mobile computing devices, such as personal digital assistants (PDA) and other handheld devices, do not take full advantages of the pen technology offered by these devices. Instead, input of expressions is still done through a virtual keypad shown on the screen, and the stylus (i.e., electronic pen) is simply used as a pointing device. In this paper we propose an intelligent handwriting-based calculator program with which the user can enter expressions simply by writing them on the screen using a stylus. In addition, variables can be defined to store intermediate results for subsequent calculations, as in ordinary algebraic calculations. The proposed software is the result of a novel application of on-line mathematical expression recognition technology which has mostly been used by others only for some mathematical expression editor programs