function polyStr = getRequiredPolynomialsForModelStructure(modelStructure)
% getRequiredPolynomialsForModelStructure Helper function that contains the
% polynomials used in a given discrete time model structure
%
%   getRequiredPolynomialsForModelStructure(modelStructure)
%   
%   Inputs:
%     modelStructure - A descriptor string for the model structure

%   Copyright 2013-2014 The MathWorks, Inc.
switch lower(modelStructure)
    case 'ar'
        polyStr = {'A0'};    
    case 'arx'
        polyStr = {'A0','B0'};
    case 'arma'
        polyStr = {'A0','C0'};        
    case 'armax'
        polyStr = {'A0','B0','C0'};
    case 'oe'
        polyStr = {'B0','F0'};
    case 'bj'
        polyStr = {'B0','F0','C0','D0'};        
    otherwise
        error(message('Ident:simulink:recursiveEstimationInternalError',...
            ['Invalid model structure: ' modelStructure]));
end
end
