matlab用设计一个信号发生器,并同时画出信号的时域表示，自相关函数及功率谱。白噪声,单位冲激信号,正弦信号,方波信号,三角波信号-matlab design with a signal generator, and at the same time draw time-domain signal representation, the autocorrelation function and power spectrum. White noise, unit impulse signal, sine signal, square wave signal, triangular wave signal