You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: get_lnRevIdx.m
    path of file: ./repos/yeast-GEM/code/.deprecated/modelCuration
    
    the code of the file until where you have to start completion: function rxn_lnRevIdx = get_lnRevIdx(deltaG,rxn,model)
% get_lnRevIdx
%   Calculates the log-scale reversibility index of a reaction
%   Reference to paper by Noor et al., doi:10.1093/bioinformatics/bts317
%   
%   deltaG      Gibbs free energy of reaction
%   rxn         Identifier in model.rxns e.g. r_0001
%   model       COBRA model structure
%
%   Usage: rxn_lnRevIdx = get_lnRevIdx(deltaG,rxn,model)
%


    
function rxn_lnRevIdx = get_lnRevIdx(deltaG,rxn,model)
% get_lnRevIdx
%   Calculates the log-scale reversibility index of a reaction
%   Reference to paper by Noor et al., doi:10.1093/bioinformatics/bts317
%   
%   deltaG      Gibbs free energy of reaction
%   rxn         Identifier in model.rxns e.g. r_0001
%   model       COBRA model structure
%
%   Usage: rxn_lnRevIdx = get_lnRevIdx(deltaG,rxn,model)
%

%define constants
R = 8.3145e-3; %gas constant (in kJ/K·mol)
T = 298.15; %temperature at standard conditions (in K)
C = 1e-3; %characteristic physiological concentration (in M)
if nargin~=3
    warning('Incorrect input: deltaG and corresponding identifier model.rxns required');
else
    if isa(deltaG,'double')
        deltaG = deltaG*4.184; %unit conversion from kcal/mol to kJ/mol
        %find number of reactants
        rxn_idx = find(ismember(model.rxns,rxn));
        met_idx = find(model.S(:,rxn_idx));
        coef = model.S(met_idx,rxn_idx);
        N_sub = 0;
        N_pdt = 0;
        for j = 1:length(coef)
            if coef(j) <= -1
                N_sub = N_sub + 1;
            elseif coef(j) >= 1
                N_pdt = N_pdt + 1;
            end