function gam = eml_hds(Gb, ci, ri, hds)%function gam = eml_hds(Gb, ci, ri, hds)% precompute hidden data space factor, based on 1995 PML SAGE paperif nargin < 4, help(mfilename), error(mfilename), endif iscell(ci)	gam = inf;	nblock = block_op(Gb, 'n');	for ii=1:nblock		gam_new = eml_hds_1(Gb{ii}, ci{ii}, ri{ii}, hds);		gam = min(gam, gam_new);	endelse	gam = eml_hds_1(Gb, ci, ri, hds);end%% eml_hds_1()%function gam = eml_hds_1(Gb, ci, ri, hds)if hds == 1	gam = 0;elseif hds == 3	ai = ci(:) .* col(Gb * ones(size(Gb,2),1)); % sum_j \aij	gam = min(ri(ai~=0) ./ ai(ai~=0));else	error 'bad hds'end