function [siz, str] = findGroups3d(ARRAY)

% findgroups3d(<array>) - Sort array into groups and report the groups
%
% The findgroups3d function produces a structure in which each element
% (row) of the structure is a list array of all the individuals (fish #)
% who are together in a single group. The group is defined as being within
% d distance from each other. The algorithm treats individuals as being in
% the same group if they are within d cm from each other, and chains 
% the searching together so that if x is d cm from y and y is d cm from z,
% then x, y, and z are in one group, even though dist(x,z) > 5 cm.

ARRAY = [zeros(size(ARRAY,1),1) ARRAY];

d = sqrt(3.125*pi) * (5/3); 

% Pick a fish to start with. #1 is as good as any.
f = 1;			% Individual number
g = 1; 			% group number

% Square the straggler distance, d
dsq = d*d;

% Make a temporary "active matrix" to hold the array of values in,
% so that we aren't editing ARRAY. Make sure the ARRAY is sorted
% by individual #, and then delete all the parts of the ARRAY that
% are not necessary (assuming it's in RANDFISH format...)

MTX = sortrows(ARRAY,2);
MTX = ARRAY(:,1:5);

group(g).members = [];
TRIED_PTS = [];

sz = size(MTX,1);

% Cycle until no fish remain to be categorized into a group

while ( sz > 0 )
	% Find the coordinates of the focal fish
	fx = ARRAY(f,3);
	fy = ARRAY(f,4);
	fz = ARRAY(f,5);
	
	% Cycle over everyone but fish f, and see who is < d distance
	% from him
	
	for i = 1:sz
		ix = MTX(i,3);
		iy = MTX(i,4);
		iz = MTX(i,5);
		
		% Find the squared distance and see if it is less than 
		% the squared 'straggler distance'.
		dist_fi = (fx - ix)^2 + (fy - iy)^2 + (fz - iz)^2;
		
		if ( dist_fi < dsq )
			TMP = group(g).members;
			TMP = [TMP, MTX(i,2)];
			group(g).members = TMP;
		end
	
	end

	% We have now found everyone who is within the d distance of individual f.
	% We can therefore remove individual f from MTX, since it is no longer needed.
	% Find the row containing individual f:
	rownum = find(MTX(:,2) == f);
	MTX(rownum,:) = [];
	TRIED_PTS = [TRIED_PTS, f];
	GRP = setdiff(group(g).members, TRIED_PTS);
	
	for j = GRP
		% Before we can look to see if anyone else in the group is < 5 BL from one of
		% these guys, these guys can all be eliminated from the MTX
		% array.
		rownum = find(MTX(:,2) == j);
		MTX(rownum,:) = [];
	end

	% Now, if there is anyone else left in the group, we pick the first
	% fish and try this again, seeing if there is anyone else who is within
	% d distance of him.
	
	if ( size(GRP,2) == 0 )
		% Pick a new fish -- just take the next one in line, if
		% there is one If not, we can ignore it.
		if ( isempty(MTX) == 0 )
			f = find(ARRAY(:,2) == MTX(1,2));
			
			% There's no one left in the group, so we need to pick a new group
			g = g + 1;		
			group(g).members = [];
			
		end
	
	else
		% There's still at least 1 fish in the present group, g, so we can
		% see if he has any neighbors
       
		f = find(ARRAY(:,2) == GRP(1));
	end


	sz = size(MTX,1);
end

siz = g;
str = group;