function [ys,params,info] = evaluate_steady_state_file(ys_init,exo_ss,M,options,steady_state_checkflag)
% function [ys,params1,info] = evaluate_steady_state_file(ys_init,exo_ss,M,options,steady_state_checkflag)
% Evaluates steady state files
%
% INPUTS
%   ys_init                   vector           initial values used to compute the steady
%                                                 state
%   exo_ss                    vector           exogenous steady state
%   M                         struct           model parameters
%   options                   struct           options
%   steady_state_checkflag    boolean          indicator whether to check steady state returned
% OUTPUTS
%   ys                        vector           steady state
%   params1                   vector           model parameters possibly
%                                              modified by user steadystate
%                                              function
%   info                      2x1 vector       error codes
%
% SPECIAL REQUIREMENTS
%   none

% Copyright © 2001-2022 Dynare Team
%
% This file is part of Dynare.
%
% Dynare is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% Dynare is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with Dynare.  If not, see <https://www.gnu.org/licenses/>.

params = M.params;
info = 0;

fname = M.fname;

if options.steadystate_flag == 1
    % old format
    assignin('base','tmp_00_',params);
    evalin('base','M_.params=tmp_00_; clear(''tmp_00_'')');
    h_steadystate = str2func([fname '_steadystate']);
    [ys,params1,check] = h_steadystate(ys_init, exo_ss,M,options);
else % steadystate_flag == 2
     % new format
    h_steadystate = str2func([fname '.steadystate']);
    [ys,params1,check] = h_steadystate(ys_init, exo_ss, params);
end

if check
    info(1) = 19;
    info(2) = NaN;
    return
end

if M.param_nbr > 0
    updated_params_flag = max(abs(params1-params)) > 1e-12 ...
        || ~isequal(isnan(params1),isnan(params)); %checks whether numbers or NaN changed
else
    updated_params_flag = 0;
end

if M.set_auxiliary_variables
    % Define function handle for the function setting the auxiliary
    % variables only if the model has auxiliary variables. Otherwise
    % Octave may crash (see https://savannah.gnu.org/bugs/?52568) because
    % the function does not exist in the path.
    h_set_auxiliary_variables = str2func([M.fname '.set_auxiliary_variables']);
end

if  isnan(updated_params_flag) || (updated_params_flag  && any(isnan(params(~isnan(params))-params1(~isnan(params))))) %checks if new NaNs were added
    info(1) = 24;
    info(2) = NaN;
    if M.set_auxiliary_variables
        ys = h_set_auxiliary_variables(ys,exo_ss,params);
    end
    return
end

if updated_params_flag && ~isreal(params1)
    info(1) = 23;
    info(2) = sum(imag(params).^2,'omitnan');
    if M.set_auxiliary_variables
        ys = h_set_auxiliary_variables(ys,exo_ss,params);
    end
    return
end

if updated_params_flag
    params = params1;
end

% adding values for auxiliary variables
if ~isempty(M.aux_vars) && ~options.ramsey_policy
    if M.set_auxiliary_variables
        ys = h_set_auxiliary_variables(ys,exo_ss,params);
    end
end

if steady_state_checkflag
    % Check whether the steady state obtained from the _steadystate file is a steady state.
    [residuals, check] = evaluate_static_model(ys, exo_ss, params, M, options);
    if check
        info(1) = 19;
        info(2) = check; % to be improved
        return
    end
    if max(abs(residuals)) > options.solve_tolf
        info(1) = 19;
        info(2) = residuals'*residuals;
        return
    end
    if any(isnan(residuals))
        info(1) = 22;
        return
    end
elseif ~isempty(options.steadystate_partial)
    ssvar = options.steadystate_partial.ssvar;
    nov   = length(ssvar);
    indv  = zeros(nov,1);
    for i = 1:nov
        indv(i) = strmatch(ssvar(i), M.endo_names, 'exact');
    end
    ys = dynare_solve('restricted_steadystate', ys(indv), options.steady.maxit, options.dynatol.f, options.dynatol.x, options, exo_ss, indv);
end