greg2jul.m

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function JD=greg2jul(GD)
%GREG2JUL  Transform Gregorian date to Julian date.
%   JD = GREG2JUL(GD) transforms Gregorian date GD to
%   Julian date JD. Julian date is the number of days
%   since noon on January 1, 4712 BC, as proposed by
%   J.J. Scaliger in 1583.
%   GD can be generated either by use of DATENUM or NOW.
%
%   See also JULEPOCH, DATENUM, NOW.

% Copyright (c) 2003-06-09, B. Rasmus Anthin.

%JD=GD-datenum(-4712,1,1,12,0,0);
[Y M D]=datevec(GD);
POD=rem(GD,1);               %part of day
JD=367*Y-floor(7*(Y+floor((M+9)/12))/4) ...
   -floor(3*(floor((Y+(M-9)/7)/100)+1)/4) ...
   +floor(275*M/9)+D+1721028.5+POD;