I. Introduction
In this paper, we consider an oscillator to which multiple inputs can be applied. The multiple-inputs system would exhibit more interesting phenomena than single input systems. As a fundamental problem, it is important to recognize proper phenomena in the multiple-inputs system. It is also important to recognize basic functions of each input. If these functions can be fused efficiently in the multiple-inputs system, we may obtain more sophisticated functions than the single input systems. They will be fundamentals to develop multiple-inputs nonlinear systems, e.g., artificial neural networks, communications systems, and so on. Note that since the superposition theorem can not be applied to the nonlinear systems, the general analysis will be hard. Hence, we focus on a simple but important system and consider proper phenomena to the multiple-inputs case.