x = -1:0.05:10; y1 = sin(x); y2 = cos(x);

clf
figure(1);
plot(x,y2,'r+')
legend('cos(x)')

figure(2);
plot(x,y2,'r+',x,y1,'b+-', x,y1.*y2)
legend('cos(x)','sin(x)','sin(x)*cos(x)')
title('Some Plots');
xlabel('Distance'); ylabel('Amplitude');
grid on

om = logspace(0,4,201);
g = om./((100-i*om).*((om.^2-1e4+i*30*om).^2));
figure(3);
clf
semilogx(om,20*log10(abs(g)))
grid on
title('A Bode Plot')
xlabel('frequency [rad/sec]')
ylabel('amplitude [dB]')
