function [gtime]=gregorian(julian)

%GREGORIAN  Converts Julian day numbers to corresponding

%       Gregorian calendar dates.  Although formally, 

%       Julian days start and end at noon, here Julian days

%       start and end at midnight for simplicity.

%     

%       In this convention, Julian day 2440000 begins at 

%       0000 hours, May 23, 1968.

%

%     Usage: [gtime]=gregorian(julian) 

%

%        julian... input decimal Julian day number

%

%        gtime is a six component Gregorian time vector

%          i.e.   gtime=[yyyy mo da hr mi sec]

%                 gtime=[1989 12  6  7 23 23.356]

%        yr........ year (e.g., 1979)

%        mo........ month (1-12)

%        d........ corresponding Gregorian day (1-31)

%        h........ decimal hours

%

%  calls S2HMS

      julian=julian+5.e-9;    % kludge to prevent roundoff error on seconds

%      if you want Julian Days to start at noon...

%      h=rem(julian,1)*24+12;

%      i=(h >= 24);

%      julian(i)=julian(i)+1;

%      h(i)=h(i)-24;

      secs=rem(julian,1)*24*3600;

      j = floor(julian) - 1721119;

      in = 4*j -1;

      y = floor(in/146097);

      j = in - 146097*y;

      in = floor(j/4);

      in = 4*in +3;

      j = floor(in/1461);

      d = floor(((in - 1461*j) +4)/4);

      in = 5*d -3;

      m = floor(in/153);

      d = floor(((in - 153*m) +5)/5);

      y = y*100 +j;

      mo=m-9;

      yr=y+1;

      i=(m<10);

      mo(i)=m(i)+3;

      yr(i)=y(i);

      [hour,min,sec]=s2hms(secs);

      gtime=[yr(:) mo(:) d(:) hour(:) min(:) sec(:)];

%=======================================================

function [hour,min,sec]=s2hms(secs)

%S2HMS converts seconds to integer hour,minute,seconds

%

sec=round(secs);

hour=floor(sec/3600);

min=floor(rem(sec,3600)/60);

sec=round(rem(sec,60));