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K E
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Why can't I access day, juliandate?

Asked by K E
on 4 Aug 2015
Latest activity Commented on by Walter Roberson
on 6 Aug 2015
I have R2015a and can see help for day and juliandate, but I can't access to them from Matlab, and they are not in c:\Program Files\MATLAB\R2015a\, although c:\Program Files\MATLAB\R2015a\help\matlab\ref\juliandate.html is there.
juliandate(now)
Undefined function or variable 'juliandate'.
Is there a problem with my installation? Or what do I need to obtain these programs?

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4 Answers

Answer by Sean de Wolski
on 4 Aug 2015

It's in the aerospace toolbox, are you able to pull it?
which juliandate -all
C:\Program Files\MATLAB\R2015a\toolbox\aero\aero\juliandate.m

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Answer by James Tursa
on 4 Aug 2015
Edited by James Tursa
on 4 Aug 2015

If it is just this function you need, then you could use this instead:
datenum(whatever) + 1721058.5
For day you could use datevec:
v = datevec(whatever)
d = v(:,3); % day of month

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Answer by Peter Perkins
on 5 Aug 2015

KE, day is a function in the Financial Toolbox, and juliandate is a function in the Aerospace Toolbox. The fact that you're asking about both, and have R2015a, makes me wonder if perhaps you're missing those toolboxes, but are looking at documentation for the datetime data type, which has day and juliandate methods. It's new in R2014b.
>> d = datetime('now')
d =
05-Aug-2015 13:58:38
>> day(d)
ans =
5
>> juliandate(d)
ans =
2457240.08239486
datetime is more or less a replacement for the combination of the suite of datenum/datevec/datestr functions, and in general, you want to use either datetime, or use the old functions, but not mix them.

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You are right: I don't have either toolbox. I am wondering why the help for these functions is installed since it just leads to confusion. Anyway, I will use the old datenum functions.

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Answer by Peter Perkins
on 6 Aug 2015

KE, just to be clear, if you have MATLAB R2015a, then you have datetime, along with its day and juliandate methods. No extra toolboxes needed.

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OK, that's good to know. If I can access the help for these programs, but not the programs themselves, then does this indicate a installation problem requiring a re-install of Matlab?
Is that definitely your error, and not
Undefined function 'juliandate' for input arguments of type 'double'.
or similar? juliandate() outside of those toolboxes is defined for datetime objects but not for strings or double

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