function i=tind(jd,greg,greg2);
% TIND finds index of Julian day array closest to the specified Gregorian time
%  if optional third argument, returns array of indices
%
%   Usage: i=tind(jd,greg,[greg2]);
%     
%  examples:
%    i=tind(jd,[1990 4 5 0 0 0]);
%     returns the index of jd that is closest to to 0000 April 5, 1990 
%
%    ii=tind(jd,[1990 4 5 0 0 0],[1992 3 1 12 0 0]);
%   
%    returns the indices of jd that are between 0000 April 5, 1990 
%     and 1200 March 1, 1992.
%

% Rich Signell (rsignell@usgs.gov)
% Behavior modified June 2008 to return any values in range and return NaN
% if no values of jd fall between greg and greg2
i = NaN;
jd=jd(:);
n=length(jd);
jd1=julian(greg);
if(nargin==3),
  jd2=julian(greg2);
%   if(jd2<jd(1) | jd2>jd(n)),
%    disp(' outside range')
%    return
%   end
% end
% if(jd1<jd(1) | jd1>jd(n)),
%  disp(' outside range')
%  return
% end
% if(nargin==3),
 i=find(jd>=jd1&jd<=jd2);
else
 i=near(jd,jd1,1);
end