function jd=cal2jd(yr, mn, dy)% CAL2JD  Converts calendar date to Julian date using algorithm%   from "Practical Ephemeris Calculations" by Oliver Montenbruck%   (Springer-Verlag, 1989). Uses astronomical year for B.C. dates%   (2 BC = -1 yr). Non-vectorized version. See also DOY2JD, GPS2JD,%   JD2CAL, JD2DOW, JD2DOY, JD2GPS, JD2YR, YR2JD.% Version: 24 Apr 99% Usage:   jd=cal2jd(yr,mn,dy)% Input:   yr - calendar year%          mn - calendar month%          dy - calendar day (including factional day)% Output:  jd - jJulian dateif nargin ~= 3  warning('Incorrect number of arguments');  return;endif mn > 2  y = yr;  m = mn;else  y = yr - 1;  m = mn + 12;enddate1=4+31*(10+12*1582);   % Last day of Julian calendar (1582.10.04)date2=15+31*(10+12*1582);  % First day of Gregorian calendar (1582.10.15)date=dy+31*(mn+12*yr);if date <= date1  b = -2;elseif date >= date2  b = fix(y/400) - fix(y/100);else  warning('Dates between October 5 & 15, 1582 do not exist');  return;endif y > 0  jd = fix(365.25*y) + fix(30.6001*(m+1)) + b + 1720996.5 + dy;else  jd = fix(365.25*y-0.75) + fix(30.6001*(m+1)) + b + 1720996.5 + dy;end