seconds2date.m

function date = seconds2date(secondsSinceYYYY, startYear)
% % 
% % Calculate a date string of fixed formate to the number of seconds since 00 UTC
% % of 01 January of a given year. 
% % 
% % Input parameter(s):
% % date : date and time string of the formate YYYY-MM-DDTHH:MM:SS*;
% %        any characters at the end (*) are not used
% % startYear (optional) : year from which on seconds will be calculated
% % 
% % Output parameter(s):
% % secondsSinceYYYY : Number of seconds since input start year

if nargin < 2
   startYear = 1970;
end

% Number of years
yyyy = startYear;
nSeconds = 0;
while nSeconds < secondsSinceYYYY
    if (mod(yyyy,4)~=0)
        daysPerYear = 365;
    else
        daysPerYear = 366;
    end
    if (nSeconds + daysPerYear * 86400 > secondsSinceYYYY)
        %disp('in here')
        break; % don't add any more seconds
    else
        nSeconds = nSeconds + daysPerYear * 86400;
    end
    yyyy = yyyy + 1;
end
nYears = yyyy;
restSeconds = secondsSinceYYYY - nSeconds;

% Number of months
mm = 1;
daysPerMonth = [31 28 31 30 31 30 31 31 30 31 30 31];
nSeconds = 0;
while nSeconds < restSeconds
    if ( mod(yyyy,4)==0 && mm==2 )
        DPM = 29;
    else
        DPM = daysPerMonth(mm);
    end
    if (nSeconds + DPM * 86400 > restSeconds)
        break; % don't add any more seconds
    else
        nSeconds = nSeconds + DPM * 86400;
    end
    mm = mm + 1;
end
nMonths = mm;
restSeconds = restSeconds - nSeconds;

% Number of days
dd = 1;
nSeconds = 0;
while nSeconds < restSeconds
    if (nSeconds + 86400 > restSeconds)
        break; % don't add any more seconds
    else
        nSeconds = nSeconds + 86400;
    end
    dd = dd + 1;
end
nDays = dd;
restSeconds = restSeconds - nSeconds;

% Number of hours
hh = 0;
nSeconds = 0;
while nSeconds < restSeconds
    if (nSeconds + 3600 > restSeconds)
        break; % don't add any more seconds
    else
        nSeconds = nSeconds + 3600;
    end
    hh = hh + 1;
end
nHours = hh;
restSeconds = restSeconds - nSeconds;

% Number of minutes
min = 0;
nSeconds = 0;
while nSeconds < restSeconds
    if (nSeconds + 60 > restSeconds)
        break; % don't add any more seconds
    else
        nSeconds = nSeconds + 60;
    end
    min = min + 1;
end
nMinutes = min;
restSeconds = restSeconds - nSeconds;

% Number of seconds
nSeconds = fix(restSeconds);

%restSeconds = restSeconds - nSeconds

date = [num2str(nYears,'%4d'),'-',num2str(nMonths,'%02d'),'-',num2str(nDays,'%02d'),' ',...
    num2str(nHours,'%02d'),':',num2str(nMinutes,'%02d'),':',num2str(nSeconds,'%02d')];