function?[fsf]=?T2F（tst）?
%This?is?a?function?using?the?FFT?function?to?calculate?a?signal‘s?Fourier?
%Translation?
%Input?is?the?time?and?the?signal?vectorsthe?length?of?time?mu?st?greater??
%than?2?
%Output?is?the?frequency?and?the?signal?spectrum?
dt?=?t（2）-t（1）;?