plot discrete time domain signals

6 vues (au cours des 30 derniers jours)
Jinquan Li le 14 Fév 2021
Commenté : Paul Hoffrichter le 15 Fév 2021
Given n=[-1:0.01:10]. Plot the discrete time domain signal: y[n]=e^(-n)*u(n).
Below is my program but i'm not sure if it's correct since this is my fisrt time learning Matlab. Please help. Thanks!
n=-1:0.01:10;
y=exp(-n).*heaviside(n);
stem(t,y)
1 commentaireAfficher -1 commentaires plus anciensMasquer -1 commentaires plus anciens
Paul le 14 Fév 2021
Modifié(e) : Paul le 15 Fév 2021
Be careful using heaviside for u[n]. In control systems and signal processing the function u[n] is the unit step function that is (typically) defined as
u[n] = 1 for n >= 0
u[n] = 0 for n < 0.
However, the default defintion of the heaviside function in Matlab has heaviside(0) = 0.5., which is clearly seen in the plot. Is that the desired answer?
Also, it looks a bit peculiar to have non-integer values of n. Please make sure that's the correct problem statement.

Connectez-vous pour commenter.

Réponse acceptée

Paul Hoffrichter le 14 Fév 2021
I recommend using following substitutions:
plot(t,y)
axis( [-1 10 0 1])
6 commentairesAfficher 4 commentaires plus anciensMasquer 4 commentaires plus anciens
Paul Hoffrichter le 15 Fév 2021
Just be careful as to how u(n) is defined. As @Paul mentioned, "heaviside(0) = 0.5., which is clearly seen in the plot. Is that the desired answer?". As you know, e^(-0) is 1, not 0.5, so it is up to you to decide whether your u(n) is defined the way you want it to be defined. If it is a unit step function, where u(0) is 1, then using the heaviside without adjustments leads to an incorrect value for y(n) when n is 0.
Paul Hoffrichter le 15 Fév 2021
Take a look at
The following defines the myStep function so that myStep(0) is 0 instead of 0.5.
myStep = @(n) (n>0);
If you wanted a value of 1 at n = 0, then you could use this instead:
myStep1 = @(n) (n>=0);

Connectez-vous pour commenter.

Catégories

En savoir plus sur Spectral Measurements dans Help Center et File Exchange

R2018a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by