How can I plot the orbit of Earth over the course of a year using Julian dates?

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The error I get:
Unrecognized function or variable 't_0'.
Error in MHCP_parametricEarth (line 2)
t = linspace (t_0,(1/366),t_0+1);
What I am attempting to do:
Graph the orbit of Earth over 1 year so that its path over a day shows up every 0.01 seconds.
My code:
t_o = juliandate(2020,10,13);
t = linspace (t_0,(1/366),t_0+1);
x=150*cos(2*pi(t-t_o));
y=150*sin(2*pi(t-t_o));
tcounter=0;
while tcounter<=1
plot([x(tcounter) x(tcounter + 1/365)], [y(tcounter) y(tcounter + 1/365)])
tcounter = tcounter + 2/365
pause(0.01)
end
  1 Comment
Rebekah Ericson
Rebekah Ericson on 13 Nov 2020
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

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Accepted Answer

Cris LaPierre
Cris LaPierre on 13 Nov 2020
The error you shared is because you defined t_o (uses the letter O), but then try to calculate something using t_0 (uses the number 0).
  2 Comments
Cris LaPierre
Cris LaPierre on 13 Nov 2020
Pretty soon, you're going to encounter the following error:
  • Array indices must be positive integers or logical values.
See my answer here.
Cris LaPierre
Cris LaPierre on 13 Nov 2020
Edited: Cris LaPierre on 13 Nov 2020
Check your while loop condition. What is the value of t_0 just before the loop begins?

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