network_find_ext_metabolites.m

％The Metabolic Networks Toolbox contains functions to create, ％modify, display, and simulate bioche

% [external_metabolites,external_fluxes] = network_find_ext_metabolites(network)
%
% determine metabolites and fluxes that should be set external for consistency

function [external_metabolites,external_fluxes] = network_find_ext_metabolites(network)

d_rev   = network.N * diag(network.reversible);
d_irrev = network.N - d_rev;
d1      = sum(d_rev~=0,2);
d2      = sign(sum(d_irrev>0,2));
d3      = sign(sum(d_irrev<0,2));

external_metabolites = find(2*d1+d2+d3<2);
external_fluxes      = find(sum(network.N(external_metabolites,:)~=0))';