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%?Estimate?the?sparse?signal?x?using?pruned?MMP
%
%?y			:?observation
%?Phi		:?Sensing?matrix
%?K			:?Sparsity
%?L			:?The?size?of?expanding?tree
%?cand_len	:?The?pruning?size?of?candidate?dictionareis
%
%	Output?parameters
%?x_mmp_s	:?estimated?signal
%?x_supp	:?selected?support?vector?indice.
%?idx_depth	:?iteration?count?during?estimating
%
%?Written?by?Suhyuk?Kwon
%?Information?System?Lab.?Korea?Univ.
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function?[x_mmp_s?x_supp?idx_depth]?=?islsp_EstMMP_BF_reuse（y?Phi?K?L?N_max）
	
	[nRows?nCols]	=?size（Phi）;

	idx_depth		=?0;

	%%?Define?the?hash?function?for?performance?issues.
	my_hash_f	=?@sum;
	
	s_path_info				=?struct（	‘supps‘?zeros（K1）...
										‘residu‘?zeros（nRows?1）...
										‘x_hat‘?zeros（nCols?1）...
										‘prev_inv‘?zeros（1?1）...
										‘res_norm‘?zeros（1?1）...
										‘suppHash‘?int32（0））;

	nodes_parents		=?s_path_info（:ones（L?1））;
	?
	%%?Initialize?the?best?path.
	[supp_mag?supp_idx]	=?sort（abs（Phi‘*y）?‘descend‘）;
	for?idx=1:L
		supps	=?supp_idx（idx）;
		
		x_hat	=?pinv（Phi（:supps））*y;
		residu	=?y-x_hat*Phi（:supps）;
		
		nodes_parents（idx）.supps	=?supps;
		nodes_parents（idx）.residu	=?residu;
		nodes_parents（idx）.x_hat	=?x_hat;
		nodes_parents（idx）.prev_inv	=?1/（norm（Phi（:supps））^2）;
		nodes_parents（idx）.res_norm	=?norm（residu）;
		nodes_parents（idx）.suppHash	=?my_hash_f（supps）;
	end

	%%?General?iteration
	idx_abs_child	=?L;
	
	while?（idx_depth?		idx_depth	=?idx_depth+1;
		
		search_len	=?min（idx_abs_child?N_max）;

		%nodes_children（search_len*L）	=?s_path_info;
		nodes_children		=?s_path_info（:ones（search_len*L?1））;
		
		idx_abs_child			=?0;
		for?idx_best=1:search_len
			[supp_mag?supp_idx]	=?sort（abs（Phi‘*nodes_parents（idx_best）.residu）?‘descend‘）;

			%?Generate?the?child?nodes
			for?idx_child=1:L
				%?supps	=?union（best_path_par（idx_best）.supps?supp_idx（idx_child））;
				
				%?check?exist