datenum problem in matlab

Hi,

I have a problem in a Matlab code. I import dates from excel, then Matlab "reads" them with datestr, but after that, when Matlab convert them to numbers with datenum I have problem. The format of dates are 01/01/2012. When a day of a date is from 13 of a month till the end of the month Matlab read the day as 06/03/0021 or 06/04/0034. From 1st of a motnh till 12 of the month a have no problem because it convert the days to numbers correct..

When I run the code without importing dates from excel, I put them manually on editor I don't have any problem..

Please help me!

Answer 1

[Pedro Villena]

 str = '01/01/2012'; %%string of the date, read from XLS file

First, you have to specify the date format that you have in your XLS file ( Control Panel >> Regional Configuration ).

 format = 'dd/mm/yyyy';

or

 format = 'mm/dd/yyyy';

Then, you could convert the date to number, and the number to date, without mistakes

 str = '01/01/2012'; %%string of the date, read from XLS file
 n = datenum(str,format); 
 s = datestr(n,format);  %%s must be the equal to str

Answer 2

[Titus Edelhofer]

Hi,

my guess is that your data is of the form dd/mm/yyyy, so first the day, then month, then year. But if you omit the date format when calling datenum, datenum guesses your data to be of American format (month first, so mm/dd/yyyy). That's why the first 12 will work (but give again guessing a wrong number!). To make the long story short, use the specific date format string as Pedro suggested.

Titus

Answer 3

[Niki-Kuriaki Tsaprazi]

Pedro and Titus, thank you very much for your answers. You help me a lot!! Now, my matlab file works correctly. Thank you very much!