t1 = 0 : 0.01 : 5-0.1; t2 = 5 : 0.01 : 10-0.1; t3 = 10 : 0.01 : 15-0.1; t4 = 15 : 0.01 : 20-0.1; x1 = cos(2*pi*7*t1); x2 = 0.5* cos(2*pi*14*t2); x3 = 2*cos(2*pi*21*t3); x4 = 4*cos(2*pi*28*t4); plot(t1,x1);hold on; plot(t2,x2);hold on; plot(t3,x3);hold on; plot(t4,x4);hold on; title('½Ã°£¿¡ µû¶ó Á֯ļö°¡ º¯ÇÏ´Â cosine ½ÅÈ£') xlabel('time(s)') ylabel('Amplitude') plot(0:100/1024:100-100/1024,abs(fft(x1,1024))); hold on; plot(0:100/1024:100-100/1024,abs(fft(x2,1024)),'r'); hold on; plot(0:100/1024:100-100/1024,abs(fft(x3,1024)),'k'); hold on; plot(0:100/1024:100-100/1024,abs(fft(x4,1024)),'g'); hold on; title('À§ ±×¸² FFT') xlabel('frequency(Hz)') ylabel('Amplitude')