%--------------------------------------------------------------------------
%
% Mjday: Modified Julian Date from calendar date and time
%
% Inputs:
% year, month, day, hour, min, sec
%
% output:
% Mjd Modified Julian Date
%
% Last modified: 2015/08/12 M. Mahooti
%
%--------------------------------------------------------------------------
function Mjd = Mjday(year, month, day, hour, min, sec)
if (nargin < 4)
hour = 0;
min = 0;
sec = 0;
end
y = year;
m = month;
b = 0;
c = 0;
if (m <= 2)
y = y - 1;
m = m + 12;
end
if (y < 0)
c = -.75;
end
% check for valid calendar date
if (year < 1582)
% null
elseif (year > 1582)
a = fix(y / 100);
b = 2 - a + floor(a / 4);
elseif (month < 10)
% null
elseif (month > 10)
a = fix(y / 100);
b = 2 - a + floor(a / 4);
elseif (day <= 4)
% null
elseif (day > 14)
a = fix(y / 100);
b = 2 - a + floor(a / 4);
else
fprintf('\n\n this is an invalid calendar date!!\n');
return
end
jd = fix(365.25 * y + c) + fix(30.6001 * (m + 1));
jd = jd + day + b + 1720994.5;
jd = jd + (hour+min/60+sec/3600)/24;
Mjd = jd - 2400000.5;
