clear;clc;close all;
N=512;
z=zeros(1,N);
z(1,[129:256])=sin((abs([128:255]-128).^1.7)/128);
z(1,[385:448])=sin((abs([384:447]-128).^2)/128);
subplot(211);plot(z);axis tight
z_hat=fft(z);
subplot(212);plot(abs(z_hat));axis tight;