I am pretty new on MATLAB and want to plot an exponentially sinusoidal signal Can someone help me. Thank you.

 x(t) = 20sin(2000πt − π/3)e^-at  where the values of a = 500,750,1000 with x(t) -2<t<2.

Answer 1

[Image Analyst]

Try this:

t = linspace(-2, 2, 400);
for a = [500,750,1000]
  x = 20*sin(2000 * pi* t - pi/3) .* exp(-a*t);
  plot(t, x, 'b-');
  hold on;
end
grid on;
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'Outerposition', [0, 0, 1, 1]);

Of course those are some pretty big attenuations and it drops to zero almost immediately.

[limm10]

Thank you a lot, here i want to ask some few question to understand better. You add 400 to linspace (-2,2,400). What is it exactly for? And also in plot, you add 'b-'. What it functions while ploting?

[Image Analyst]

That says that there will be 400 data points in between -2 and 2. If you just did t = -2:2 then the only values you will get are -2,-1,0,1,and 2, which is not enough to see how this curve behaves everywhere.

b means plot in blue color. - means put a solid line between all the data points. See help on plot() for other plot options. You can make it look any appearance you'd like with the proper options.