Thank you for the answer. I have changed that and edited my code, but it is still not plotting right. It will run, but it's not giving a graph or anything. It will just store numbers in the workspace, and t, x, and y are all 1 by 0 vectors here.
jd = juliandate(2020,10,13)
t_0 = jd
jd_2 = juliandate(2021,10,13)
t_1 = jd_2
t = linspace (jd, jd_2, 1/366)
x=150*cos(2*pi*(t-t_0));
y=150*sin(2*pi*(t-t_0));
tcounter=t_0;
while tcounter<=1
plot([x(tcounter) x(tcounter+1/365)], [y(tcounter) y(tcounter + 1/365)])
hold on
tcounter = tcounter + 2/365
pause(0.01)
end