In the theory of the system, the tools of Fourier analysis or Fourier transform enable us to analyze the response of a LTI system, such as a circuit, to such sinusoidal inputs.

• 在系统理论中,付里叶分析与付里叶变换的工具使我们能够对一个线性时不变系统在正弦激励下的响应进行分析,比如一个电路对正弦输入下的响应。