< Code >

pi = 3.14159;

x = [-2*pi:pi/200:2*pi];

a = 20;

hFig = figure(1);

subplot(2,1,1);

y = abs(sinc(x) .* cos(x/5));

plot(x,y,'b-','linewidth',2); grid on; xlabel('x'); ylabel('y');

xlim([-2*pi  2*pi]);

ylim([0 1]);

subplot(2,1,2);

y = a * log10(abs(sinc(x) .* cos(x/5)));

plot(x,y,'b-','linewidth',2); grid on; xlabel('x'); ylabel('y');

xlim([-2*pi  2*pi]);

ylim([-80 0]);

%set(gca,'xtick',1:1:10);

pos = [(i/50.0) 0.01 (1.0/50.0) 0.98];

set(hFig,'Position',[300 400 800 500])