% - - - - - - - - - -

% i a u C a l 2 j d

% - - - - - - - - - -

%

% Gregorian Calendar to Julian Date.

%

% This function is part of the International Astronomical Union's

% SOFA (Standards Of Fundamental Astronomy) software collection.

%

% Status: support function.

%

% Given:

% year, month, day in Gregorian calendar (Note 1)

%

% Returned:

% djm0 MJD zero-point: always 2400000.5

% djm Modified Julian Date for 0 hrs

%

% Notes:

% 1) The algorithm used is valid from -4800 March 1, but this

% implementation rejects dates before -4799 January 1.

%

% 2) The Julian Date is returned in two pieces, in the usual SOFA

% manner, which is designed to preserve time resolution. The

% Julian Date is available as a single number by adding djm0 and

% djm.

%

% 3) In early eras the conversion is from the "Proleptic Gregorian

% Calendar"; no account is taken of the date(s) of adoption of

% the Gregorian Calendar, nor is the AD/BC numbering convention

% observed.

%

% Reference:

% Explanatory Supplement to the Astronomical Almanac,

% P. Kenneth Seidelmann (ed), University Science Books (1992),

% Section 12.92 (p604).

%

% This revision: 2009 October 19

%

% SOFA release 2012-03-01

%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function [djm0, djm] = iauCal2jd(year, month, day)

djm0 = 2400000.5;

b = 0;

c = 0;

if (month <= 2)

year = year - 1;

month = month 12;

end

if (year < 0)

c = -.75;

end

% check for valid calendar date

if (year < 1582)

% null

elseif (year > 1582)

a = fix(year / 100);

b = 2 - a floor(a / 4);

elseif (month < 10)

% null

elseif (month > 10)

a = fix(year / 100);

b = 2 - a floor(a / 4);

elseif (day <= 4)

% null

elseif (day > 14)

a = fix(year / 100);

b = 2 - a floor(a / 4);

else

fprintf('\n\n this is an invalid calendar date!!\n');

return

end

jd = fix(365.25 * year c) fix(30.6001 * (month 1));

jd = jd day b 1720994.5;

djm = jd-djm0;