function str=dateaxis(jd,base)
% function str=dateaxis(jd,base)
% converts a sequence of 'jd' julian days into a string
% of dates to plot as axis labels.
% 'base' is the initial day as [year,month,day]
% jd=0 corresponds to the base date

str=num2str(zeros(length(jd),1),'%9.9i');
jbase=julian(base(1),base(2),base(3));
jd=jd+jbase-1;
ybase=base(1);
months=['Jan';'Feb';'Mar';'Apr';'May';'Jun';'Jul';'Aug';'Sep';'Oct';'Nov';'Dec';];

for i=1:length(jd),
 [m,d]=gregorian(ybase,jd(i));
 while(m>12),
  ybase=ybase+1;
  jd(i:length(jd))=jd(i:length(jd))-julian(ybase-1,12,31);
  [m,d]=gregorian(ybase,jd(i));
 end
 sybase=num2str(ybase);
 str(i,:)=[num2str(d,'%2.2i') '.' months(m,:) '.' sybase(3:4)];
end