function yd=yearday(mon,day,leapyr)
% YEARDAY: converts calender month and day into yearday.
% yd = YEARDAY(mon,day,leapyr) converts calender month and day into yearday.
% If year is not a leap year, then omit the third input variable. If year
% is a leap year, then enter leapyr=1.
%
% INPUT:   mon    - month
%          day    - day
%          leapyr - set to 1 if it is a leap year, otherwise omit
%
% OUTPUT:  yd - year day
%
%   Examples:  15 March 1995 = yearday(3,15) = 74
%              15 March 1996 = yearday(3,15,1) = 75

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 8/19/98: version 1.1
% 8/5/99: version 2.0
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

m=mon;
d=day;

% compute yd for non-leap year
if m==1,y=d;end;
if m==2,y=31+d;end;
if m==3,y=59+d;end;
if m==4,y=90+d;end;
if m==5,y=120+d;end;
if m==6,y=151+d;end;
if m==7,y=181+d;end;
if m==8,y=212+d;end;
if m==9,y=243+d;end;
if m==10,y=273+d;end;
if m==11,y=304+d;end;
if m==12,y=334+d;end;
end
yd=y;
% adjust for leap year
if nargin > 2,
  if (leapyr==1 & m>=3)
     yd=yd+1;
  end 
end