1)门信号的傅立叶变换
>> clear all;
>> syms t w
>> ut=sym('heaviside(t+0.5)-heaviside(t-0.5)');
>> subplot(211);
>> ezplot(ut)
>> title('门信号')
>> hold on
>> axis([-1 1 0 1.1]);
>> plot([-0.5 -0.5],[0 1]);
>> plot([0.5 0.5],[0 1]);
>> fw=fourier(ut,t,w);
>> ffw=maple('convert',fw,'piecewise');
>> ffp=abs(ffw);
>> subplot(212);
>> ezplot(ffp,[-10*pi 10*pi]);
>> axis([-10*pi 10*pi 0 1.1]);
>> title('幅度频谱')
2)冲激信号的傅立叶变换及频谱