Plotting a Sequence over a Given Interval

I am trying to plot the follwing sequence,

𝑥(𝑛) = 𝑛[𝑢(𝑛) − 𝑢(𝑛 − 10)]+ 10𝑒 −0.(𝑛−10) [𝑢(𝑛 −10) − 𝑢(𝑛 − 20)]

Over this interval

0 ≤ 𝑛 ≤ 20

I already have some code from a previous attempt at this type of problem which is as follows,

% USMPL Function %
function delta = usmpl(n)
if n == 1
    delta = 1
else
    delta = 0
end

% Main Code %
n = -10:10
x = zeros(length(n) 
for k = 1:length(n)
    x(k) = 2*usmpl(n(k)+ 1) - usmpl(n(k)-6);
end

stem(n,x)

The problem I am having is working out what to put where in this code to make it work for this problem.

Thanks.

[Star Strider]

This part:

makes no sense.

Care to clarify?

[Connor Wright]

This should be

[Star Strider]

Regardless of what ‘n’ is, that simply evaluates as 10, since always evaluates as 1.

Example —

n = 42;
expr = 10*exp(-0*(n-10))

.

[Connor Wright]

So would it be feesible to just modify my USMPL code and make u the focus instead of delta?

Answer 1

[Star Strider]

I have no idea.

I would just do something like this, and hope for the best with respect to whatever that exp() call is supposed to do:

u = @(t) t>=1;
x = @(n) n.*(u(n)-u(n-10) + 10*exp(-0*(n-10)) .* (u(n-10)-u(n-20)));

n = linspace(0, 20, 1000);

figure
plot(n, x(n))
grid

Make appropriate changes when you resolve the problem with the exponential term.