match a number (date) in a matrix - Matlab

I have an interesting problem that involves taking the last day from a matrix and finding its last month day.

Eg, if the date today is Oct-10-2011, you try to search for Sep-10-2011 or the first day < Sep-10-2011 in the matrix.

Matrix has multiple IDs and last trading dates may not be the same. Vectorized solution is desired. Thanks!

mat = [ ...

      1000 734507 11 ; 
      1000 734508 12 ; 
      1000 734509 13 ; 

      2001 734507 21 ; 
      2001 734508 22 ; 
      2001 734513 23 ; 
      2001 734516 25 ;

      1000 734536 14 ; 
      1000 734537 15 ; 
      1000 734538 16 ; 

      2001 734536 26 ; 
      2001 734537 27 ; 
      2001 734544 28 ;
      2001 734545 29 ; 
      2001 734546 30 ;
];

     % datestr(mat(:,2))
     [~,m,~] = unique(mat(:,1), 'rows', 'last') ;
     lastDay = mat(m,;) ;

I tried using addtodate to get last-month-date here but it fails (more than 1 row).

Once I get the last-dates for each ID, I need to get the exact_day_lastmonth.

After this, I need to get data on this day OR the day nearest to it (should be < exact_day_lastmonth).

Answer:

current_lastdays = [1000 734538 16 ;  2001 734546 30] ; 
                 % [4-Feb-2011,       12-Feb-2011]

matching_lastmon = [1000 734507 11 ;  2001 734513 23] ; 
                 % 4-Jan-2011,        10-Jan-2011

Answer 1

[Matt Tearle]

I don't think there's a completely vectorized solution, but this is close:

d = datenum(bsxfun(@minus,datevec(lastDay(:,2)),[0,1,0,0,0,0]));
f = @(n) find(mat(:,2)<=d(n) & mat(:,1)==lastDay(n,1),1,'last');
matching_lastmon = mat(arrayfun(f,1:length(d)),:)