closest day a year back

Hi,

I have a vector of dates and my alogorithm is picking one observation X in a loop. I want to go back an exactly year back from the date of X. but the date sometimes doesn't exist because it is not a working a day and I am interested only in working days. How can I choose from this vector the closest working day which is X-365 but if it doesn't exist then it should be X-364 or X-363 etc..

Answer 1

[Star Strider]

Here's a simple routine that should work:

refdate = datenum([2012 10 16]);        % Test Day1
refdate = datenum([2012 10 15]);        % Test Day2

yearago = addtodate(refdate, -1, 'year');
[Nya, Sya] = weekday(yearago)
if Nya == 1
    yearago = addtodate(yearago, 1, 'day');
elseif Nya == 7
    yearago = addtodate(yearago, -1, 'day');
end
[NyaW, SyaW] = weekday(yearago)

The two refdate values put yearago on a Saturday or Sunday. The if block substitutes Friday for Saturday and Monday for Sunday. The yearago variable is the date number for that day.

Answer 2

[Azzi Abdelmalek]

use

 [day_number,day]=weekday(datestr(now-365))  %  date from now

or

 dat=datenum('21-Sep-2012 21:36:20')
 [day_number,day]=weekday(datestr(dat-365))  %  date from any day

Now you have a number day, Sunday=1 Monday=2,... I don't know what do you mean by not working days, do you include days other then Sunday, like, Thanksgiving