Add n days to juliandate

Hello everyone!

I am using

planetEphemeris(juliandate(y, m, d), 'Sun', 'Mars')

to extract the position of Mars relative to Sun at a given date

y, m, d.

Now, I need to add a specific number of days to that date and extract the position of the new date. Apparently,

planetEphemeris(juliandate(y, m, d) + n, 'Sun', 'Mars')

does not work. What do I need to add instead of n to have the position of Mars in, say, 100 days after that date?

Thank you in advance.

Answer 1

[Robert U]

Hi Asatur Khurshdyan,

According to documentation example juliandate() you may use caldays() to add calendar days to a datetime-date.

planetEphemeris(juliandate(datetime(y,m,d)+caldays(n)), 'Sun', 'Mars')

Kind regards,

Robert

[Asatur Khurshudyan]

Dear Robert,

Thank you for your answer. Sorry about missing that part from documentation.

Best,

Asatur

Answer 2

[Bjorn Gustavsson]

It seems to work just fine as far as I can see. When I compare:

jd0 = juliandate(2020, 2, 14);
jd0p100 =juliandate(2020, 2, 14) + 100;
jd0p101 =juliandate(2020, 2, 14 + 100);
isequal(jd0p100,jd0p101) % returns true
jd0p101 - jd0            % returns 100

everything seems OK.

What is your problem? What matlab-version are you using?

HTH