Why can't I access day, juliandate?

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K E
K E 2015-8-4
评论： Walter Roberson 2015-8-6
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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回答（4 个）

Sean de Wolski
Sean de Wolski 2015-8-4
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
James Tursa
James Tursa 2015-8-4
编辑：James Tursa 2015-8-4
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
Peter Perkins
Peter Perkins 2015-8-5
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.
  1 个评论
K E
K E 2015-8-5
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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Peter Perkins
Peter Perkins 2015-8-6
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.
  2 个评论
K E
K E 2015-8-6
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?
Walter Roberson
Walter Roberson 2015-8-6
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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