function dd=yd2dd(yd,yr)
% dd=yd2dd(yd,yr) converts yd of yr 
% into 1995 drifter day dd.
% 4/1/01

yd=yd(:);
gtime=greg2(yd-1,yr);
y=gtime(:,1);
m=gtime(:,2);
d=gtime(:,3);
h=gtime(:,4);
min=gtime(:,5);
s=gtime(:,6);
h=h+min./60+s./3600;
dd=julian(y,m,d,h)-julian(1995,1,1,0)+1;
