国外下载的，把傅里叶变换讲的清晰易懂

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Fourier Transform E Handout Four dierent forms of the Fourier transform Nonperiodic continuous time function xt continuous non periodic spectrum Xf This is the most general form of Fourier transform cid0 Xf Z xt Z cid0 xtecid0jf tdt Xf ejf tdf The rst one is the forward transform and the second one is the inverse transform Nonperiodic discrete time function xn continuous peri odic spectrum XF f The discrete time function can be considered as a sequence of samples of continuous time fun......