eomdateAN(y,m)

function d = eomdateAN(y,m) 
%EOMDATE Last date of month. Allow for negative months number 
%   D = EOMDATE(N) returns the last date of the month, in serial form,
%   given the date N.  N can be input as a serial date number or date
%   string.
%
%   D = EOMDATE(Y,M) returns the last date of the month, in serial
%   form, for the given year, Y, and month, M.  
% 
%   For example, d = eomdate(1997,2) returns d = 729449 which is the serial
%   date corresponding to February 28, 1997.
%Example (code improvment by Tal_Shir:
% eomdateAN(2007,0) will return the date of 31.12.2006
% eomdateAN(2007,-1) will return the date of 30.11.2006
% eomdateAN(2007,-12) will return the date of 31.12.2005
% eomdateAN(2007,13) will return the date of 31.01.2008

%   See also DAY, EOMDAY, LBUSDATE, MONTH, YEAR. 
 
%   Copyright 1995-2006 The MathWorks, Inc.
%        $Revision: 1.7.2.3 $   $Date: 2008/05/31 23:18:09 $

% Check number of input arguments
if nargin < 1
  error('finance:eomdate:missingInputs','Please enter N or enter Y and M.') 
end 

% Date input
if nargin == 1
  [yr,mt] = datevec(y);
  ld = eomday(yr,mt);
  d = datenum(yr,mt,ld);
  return
end

% Year and month input

if length(y)==1;y = y(ones(size(m)));end   % scalar expansion
if length(m)==1;m = m(ones(size(y)));end
if length(y)==1;y = y(ones(size(m)));end   
if checksiz([size(y);size(m)],mfilename)
  return
end

if m==0
    ld = eomday(y-1,12);
    d = datenum(y-1,12,ld);
    return
end

if m<0
    YearBack=floor(abs(m)/12)+1;
    m=YearBack*12+m;
    y=y-YearBack;
    ld = eomday(y,m);
    d = datenum(y,m,ld);
    return
end
    
if m>12
    YearFrw=ceil(m/12)-1;
    m=m-YearFrw*12;
    y=y+YearFrw;
    ld = eomday(y,m);
    d = datenum(y,m,ld);
    return
end

ld = eomday(y,m);
d = datenum(y,m,ld);