Peculiar behavior of lookfor

Question

dpb 2014-9-17

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/155214-peculiar-behavior-of-lookfor

评论： dpb 2014-9-18

Given the following function definition

function is=isleapyr(yr)
%  returns T for input date being a leapyear
is=(datenum(yr+1,1,1)-datenum(yr,1,1))==366;

Why the following output from lookfor?

>> lookfor leap
isleapyr                       - returns T for input date being a leapyear
isleapyr                       - returns T for input date being a leapyear
>> help isleapyr
 returns T for input date being a leapyear
>>

That is, where does the doubled listing come from? I've ensured there's only one copy of isleapyr.m extant in the entire Matlab installation directory. It's annoying and apparently some sort of a bug???? OBTW, R2012b.

Well, the latter comment got me thinking -- so I copied the file to a working directory in my old R12 release and voila!!

>> lookfor leap
isleapyr.m: %  returns T for input date being a leapyear
>> isleapyr(2004)
ans =
   1
>> which isleapyr
C:\matlabR12\work\isleapyr.m
>>

So it appears to be some sort of introduced bug. Anybody else confirm still extant before I submit official report?

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dpb 2014-9-17

编辑：dpb 2014-9-17

I think your last supposition is correct...I hadn't noticed it was everything in the current directory with the problem previously. I just submitted the bug report; I referenced/linked to the thread here so if TMW will read it they'll see the comment. Of course, it shouldn't take long for them to uncover the recursion problem somebody introduced.

ADDENDUM

Just confirmed your hypothesis--moving out of the current directory causes the symptom to disappear.

A Jenkins 2014-9-17

I get the same behavior on 2010a and 2008a as well, so I'm not sure we can say it was recently introduced...

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Answer 1

per isakson 2014-9-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/155214-peculiar-behavior-of-lookfor#answer_152046

编辑：per isakson 2014-9-17

在 MATLAB Online 中打开

If the current directory is in the path lookfor seems to scan it twice

A little experiment in R2014a

    >> version
    ans =
    8.3.0.532 (R2014a)

With the current directory being the folder with isleapyr

>> lookfor leap
isleapyr                       - returns T for input date being a leapyear
isleapyr                       - returns T for input date being a leapyear
leapyear                       - Determine leap year.
decaydimer                     - Comparing SSA and Explicit Tau-Leaping Stochastic Solvers

and the current being another folder

>> lookfor leap
isleapyr                       - returns T for input date being a leapyear
leapyear                       - Determine leap year.
decaydimer                     - Comparing SSA and Explicit Tau-Leaping Stochastic Solvers

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per isakson 2014-9-18

"earlier" &nbsp I guess it took me too long experimenting and that you posted the comment during that period of time.

dpb 2014-9-18

Looks roughly same time as D Young's observation but I didn't see yours until later...I'd not noticed earlier that it was only in the working directory that it occurs so that was a good catch by both of you.

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