"week.m" file disapeared

I successfully used the built-in function "week.m" last week but it seems that the matlab file has now disapeared. When I try to use it (e.g. week(1)) I get the following error message: Undefined function 'week' for input arguments of type 'double'. I checked in the finance/calendar, all is there but not the week.m file nor the quarter.m..... Any idea how to recover it ?

[Matt J]

I've never used week(), but mysteriously, on my machine, the doc command can find it

>>doc week

but not help, which, or anything else. Weird...

[Arnaud Melin]

Excatly, the doc exists but that's all (so at least I know I didn't dream about it).

[Brendan Hamm]

This has to do with how classes are defined. If the class is not loaded into memory, then one cannot access its methods (it's as if they are not on the path). But you can access the documentation as the doc is not searching the MATLAB path for a file of the given name like help and which do.

Answer 1

[Brendan Hamm]

Firstly, week is indeed a function which is included in base MATLAB for versions 2014b and later. It is meant to operate on a datetime variable and not on a numeric double and therefore you get this error. You can verify that it is indeed still installed with the following command:

which week -all

This will tell you the location of all of the instances of week which MATLAB finds.

What exactly are you trying to do with the function by passing a numeric value to the function?

[Arnaud Melin]

In my script, I am using serial date numbers instead of datetime type. What I can't understand is that it worked perfectly yesterday... When I do what Titus says, using datetime type as argument, it works but I would have to modify everything for something that was working before.

[Titus Edelhofer]

Hi Arnaud,

I could imagine that someone added a simple week.m that might look like

function w = week(d, varargin)
t = datetime(d,'ConvertFrom','datenum');
w = week(t, varargin{:});

If this is the case, searching your hard disk for week.m would do the trick ;-).

Titus

[Brendan Hamm]

week never worked with Serial Date Numbers. If you wish to use this function you would have to convert your Serial Date Number to a datetime:

dNum = now % Serial Date Number
dTime = datetime(dNum,'ConvertFrom','datenum')
wk = week(dTime)

or if you prefer the use with the datenum you can use:

wk2 = weeknum(dNum)

[Brendan Hamm]

If someone had added such a function, then it would've appeared on his search path when he called:

which week

So, I doubt this is the case. He likely either had a datetime variable and used week, or he had a serial date number and used weeknum.

[Arnaud Melin]

I used serial date number with week, but I'll convert serial date number into datetime type and it should be alright. Thanks guys !

Answer 2

[Titus Edelhofer]

Hi,

EDIT: my answer below is not correct, but the comment explains what's going on.

Hmm, are you sure this is a MathWorks supplied file? I know of weekday (MATLAB) and weeknum (Financial Toolbox) but not of week ...?

Maybe you copied it from somewhere? And maybe it's just a path thing, i.e., the folder containing your week.m is not on the MATLAB search path.

Try to locate week.m on your disk and use pathtool to add the folder in MATLAB.

Titus

[Titus Edelhofer]

Sorry, I stumbled across this myself and now (with the help of the others) remember. As long as you haven't created any datetime object, the class definition is not loaded and therefore which doesn't find it. This works:

t = datetime
t = 
 14-Jul-2015 16:59:24

which week
C:\MATLAB\R2015a\toolbox\matlab\timefun\@datetime\datetime.m  % datetime method

[Brendan Hamm]

Correct, which would require the class definition is loaded, but the doc command would not have this requirement.