function n = datenum(y,mo,d,h,mi,s)
%DATENUM Serial date number.
%   N = DATENUM(S) converts the string S into a serial date number.
%   Date numbers are serial days where 1 corresponds to 1-Jan-0000.
%   The string S must be in one of the date formats 0,1,2,6,13,14,
%   15,16 (as defined by DATESTR). Date strings with 2 character years
%   are interpreted to be within the 100 years centered around the 
%   current year.
%
%   N = DATENUM(S,PIVOTYEAR) uses the specified pivot year as the
%   starting year of the 100-year range in which a two-character year
%   resides.  The default pivot year is the current year minus 50 years.
%
%   N = DATENUM(Y,M,D) returns the serial date number for
%   corresponding elements of the Y,M,D (year,month,day) arrays.
%   Y,M, and D must be arrays of the same size (or any can be a scalar).
%
%   N = DATENUM(Y,M,D,H,MI,S) returns the serial date number for
%   corresponding elements of the Y,M,D,H,MI,S (year,month,hour,
%   minute,second) arrays values.  Y,M,D,H,MI,and S must be arrays of
%   the same size (or any can be a scalar).  Values outside the normal
%   range of each array are automatically carried to the next unit (for
%   example month values greater than 12 are carried to years).
%
%   Examples:
%       n = datenum('19-May-1995') returns n = 728798.
%       n = datenum(1994,12,19) returns n = 728647.
%       n = datenum(1994,12,19,18,0,0) returns n = 728647.75.
%
%   See also NOW, DATESTR, DATEVEC.

%   Author(s): C.F. Garvin, 3-20-95
%   Copyright (c) 1984-98 by The MathWorks, Inc.
%   $Revision: 1.15 $  $Date: 1998/08/12 13:30:37 $

if nargin == 0
  error('Not enough input arguments.');
elseif nargin == 1
  if isstr(y)
    c = datevec(y); 
    y=c(:,1);mo=c(:,2);d=c(:,3);h=c(:,4);mi=c(:,5);s=c(:,6);
  else 
    n = y; 
    return
  end
elseif nargin == 2
  if isstr(y)
    c = datevec(y,mo); % datenum(y,pivotyear)
    y=c(:,1);mo=c(:,2);d=c(:,3);h=c(:,4);mi=c(:,5);s=c(:,6);
  else
    error('Wrong number of input arguments.');
  end
elseif nargin ==4 | nargin == 5
  error('Wrong number of input arguments.');
elseif nargin == 3
  % Do three-way scalar expansion.
  if length(y)==1, y = y(ones(size(d))); end
  if length(mo)==1, mo = mo(ones(size(y))); end
  if length(d)==1, d = d(ones(size(mo))); end
  if length(y)==1, y = y(ones(size(d))); end % Required to be sure.
  h = zeros(size(y));mi = h;s = h;
end

if nargin == 6
  % Do six-way scalar expansion.
  if length(y)==1, y = y(ones(size(s))); end
  if length(mo)==1, mo = mo(ones(size(y))); end
  if length(d)==1, d = d(ones(size(mo))); end
  if length(h)==1, h = h(ones(size(d))); end
  if length(mi)==1, mi = mi(ones(size(h))); end
  if length(s)==1, s = s(ones(size(mi))); end

  % Required to be sure.
  if length(y)==1, y = y(ones(size(s))); end 
  if length(mo)==1, mo = mo(ones(size(y))); end
  if length(d)==1, d = d(ones(size(mo))); end
  if length(h)==1, h = h(ones(size(d))); end
  if length(mi)==1, mi = mi(ones(size(h))); end
end

sizes = [size(y);size(mo);size(d);size(h);size(mi);size(s)];
row_index = find(sizes(:,1) ~= sizes(1,1) & sizes(:,1) ~= 1);
col_index = find(sizes(:,2) ~= sizes(2,2) & sizes(:,2) ~= 1);
if ~isempty(row_index) | ~isempty(col_index)
  error('Y,M,D,H,MI,and S must all be the same size.')
end

% Make sure mo is in the range 1 to 12.
mo(mo==0) = 1;
y = y + floor((mo-1)/12);
mo = rem(mo-1,12)+1;

% Running total of days per month
cumdpm = cumsum([0;31;28;31;30;31;30;31;31;30;31;30;31]); 

% result = (365 days/year)*(number of years) + number of leap years ...
%      + days in previous months + days in this month + fraction of a day.
n = 365.*y + ...                   % Convert year, month, day to date number
    ceil(y/4)-ceil(y/100)+ceil(y/400) + reshape(cumdpm(mo),size(mo)) + ...
    ((mo > 2) & ((rem(y,4) == 0 & rem(y,100) ~= 0) | rem(y,400) == 0)) + d;

if any(h~=0) | any(mi~=0) | any(s~=0)
  n = n + (h.*3600+mi.*60+s)./86400;
end
