samer@3: function [Y,X0]=gathern(dim,n,X,varargin)
samer@3: % gathern - make big array of n arrays in a sequence
samer@3: %
samer@3: % gathern :: N:natural, seq [D] -> [E], seq [D].
samer@3: % gathern :: 
samer@3: %    D:natural   ~'the dimension along which to collect arrays',
samer@3: %    N:natural   ~'number of elements to collect',
samer@3: %    seq [D]    ~'the seq to gather',
samer@3: %    options {
samer@3: %       draw   :: boolean /0    ~'whether or not to call plotfn every iteration';
samer@3: %       plotfn :: seq [D]->handle ~'plotting function';
samer@3: %       save   :: natural /0    ~'if >0, then save state every this many interations';
samer@3: %       recover:: boolean / 0   ~'if 1, then attempt to restart from saved state'; 
samer@3: %       id     :: string  /'@gather' ~'file to save state'
samer@3: %    }
samer@3: % -> [E], seq [D].
samer@3: %
samer@3: % E is such that E(I) = D(I) if I~=N. The second return
samer@3: % is the final object in the sequence
samer@3: 
samer@3: Y=[]; i=1;
samer@3: if nargin<3 % simple version
samer@3: 	if ~isempty(X),
samer@3: 		Y=head(X); 
samer@3: 		i=1; while i<n
samer@3: 			X0=X; X=next(X0); i=i+1;
samer@3: 			if isempty(X), break; end
samer@3: 			Y=cat(dim,Y,head(X)); 
samer@3: 		end
samer@3: 	end
samer@3: else
samer@37: 	opts=options('save',0,'recover',0,'draw',0,'plotfn',@nullplot,varargin{:});
samer@3: 	draw=opts.draw;
samer@3: 	savn=opts.save;
samer@3: 	
samer@3: 	if opts.recover && exist([opts.id,'.mat'],'file')
samer@3: 		load(opts.id);		
samer@3: 		X=next(X0);
samer@3: 		fprintf('recovering from i=%d\n',i);
samer@3: 	end
samer@3: 	
samer@3: 	if savn==0 && ~draw
samer@3: 		if ~isempty(X)
samer@3: 			Y=head(X); 
samer@3: 			i=1; while i<n
samer@3: 				X0=X; X=next(X0); i=i+1;
samer@3: 				if isempty(X), break; end
samer@3: 				Y=cat(dim,Y,head(X)); 
samer@3: 			end
samer@3: 		end
samer@3: 	else
samer@3: 		if savn>0
samer@3: 			fprintf('Will save every %d iterations to %s.mat\n',savn,opts.id);
samer@3: 		end
samer@3: 
samer@3: 		if ~isempty(X)
samer@3: 			Y=head(X);
samer@3: 			i=1; while i<n
samer@3: 				X0=X; X=next(X0); i=i+1;
samer@3: 				if draw, opts.plotfn(X0); end
samer@3: 				if mod(i,savn)==0,
samer@3: 					fprintf('saving at %d.\n',i);
samer@3: 					save(opts.id,'X0','Y','opts','i','dim');
samer@3: 				end
samer@3: 				optpause(opts); 
samer@3: 				if isempty(X), break; end
samer@3: 				Y=cat(dim,Y,head(X));
samer@3: 			end
samer@3: 		end
samer@3: 		if savn>0, delete([opts.id '.mat']); end
samer@3: 	end
samer@3: 	if nargout>1, if isempty(X), X0=X; else X0=next(X); end; end
samer@3: end
samer@3: 
samer@3: function nullplot(A,B), return