I have no idea what you are doing, and I had to look up ‘stepseq’, since I have never heard of it before.
Experiment with this to get the result you want —
t=-10:10;
a = sin(2*pi*t/11);
[x1,n1] = stepseq(-1, -10, 10);
[x2,n2] = stepseq(1, -1, 19);
b = x1-x2;
h = a.*b;
subplot(2,1,2);
plot(t, h)
title('5-19_d');xlabel('t');ylabel('x[t]');
function [x,n] = stepseq(n0,n1,n2) % Copied From: <https://www.mathworks.com/matlabcentral/answers/12834-unsolved-function?s_tid=srchtitle#>
% Generates x(n) = u(n-n0); n1 <= n,n0 <= n2
% ------------------------------------------
% [x,n] = stepseq(n0,n1,n2)
%
if ((n0 < n1) | (n0 > n2) | (n1 > n2))
error('arguments must satisfy n1 <= n0 <= n2')
end
n = [n1:n2];
%x = [zeros(1,(n0-n1)), ones(1,(n2-n0+1))];
x = [(n-n0) >= 0];
end
I made several changes to get the code to produce something meaningful.
