function model_diagnostics(M_,options_,oo_)
% function model_diagnostics(M_,options_,oo_)
%   computes various diagnostics on the model 
% INPUTS
%   M_         [matlab structure] Definition of the model.           
%   options_   [matlab structure] Global options.
%   oo_        [matlab structure] Results 
%    
% OUTPUTS
%   none
%    
% ALGORITHM
%   ...
%    
% SPECIAL REQUIREMENTS
%   none.
%  

% Copyright (C) 1996-2009 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 <http://www.gnu.org/licenses/>.
  
    global jacob
    
    endo_nbr = M_.endo_nbr;
    endo_names = M_.endo_names;
    lead_lag_incidence = M_.lead_lag_incidence;
    maximum_lag = M_.maximum_lag;
    maximum_lead = M_.maximum_lead;
    
    %
    % missing variables at the current period
    %
    k = find(lead_lag_incidence(maximum_lag+1,:)==0);
    if ~isempty(k)
        disp(['The following endogenous variables aren''t present at ' ...
                 'the current period in the model:'])
        for i=1:length(k)
            disp(endo_names(k(i),:))
        end
    end
    
    %
    % check steady state
    %
    info = 0;

    it_ = M_.maximum_lag + 1 ;

    if M_.exo_nbr == 0
        oo_.exo_steady_state = [] ;
    end

    % check if ys is steady state
    tempex = oo_.exo_simul;
    oo_.exo_simul = repmat(oo_.exo_steady_state',M_.maximum_lag+M_.maximum_lead+1,1);
    if M_.exo_det_nbr > 0 
        tempexdet = oo_.exo_det_simul;
        oo_.exo_det_simul = repmat(oo_.exo_det_steady_state',M_.maximum_lag+M_.maximum_lead+1,1);
    end
    dr.ys = oo_.steady_state;
    check1 = 0;
    % testing for steadystate file
    fh = str2func([M_.fname '_static']);
    if options_.steadystate_flag
        [ys,check1] = feval([M_.fname '_steadystate'],dr.ys,...
                               [oo_.exo_steady_state; oo_.exo_det_steady_state]);
        if size(ys,1) < M_.endo_nbr 
            if length(M_.aux_vars) > 0
                ys = add_auxiliary_variables_to_steadystate(ys,M_.aux_vars,...
                                                            M_.fname,...
                                                            oo_.exo_steady_state,...
                                                            oo_.exo_det_steady_state);
            else
                error([M_.fname '_steadystate.m doesn''t match the model']);
            end
        end
        dr.ys = ys;
    else
        % testing if ys isn't a steady state or if we aren't computing Ramsey policy
        if  options_.ramsey_policy == 0
            if options_.linear == 0
                % nonlinear models
                if max(abs(feval(fh,dr.ys,[oo_.exo_steady_state; ...
                                        oo_.exo_det_steady_state], M_.params))) > options_.dynatol
                    [dr.ys,check1] = dynare_solve(fh,dr.ys,1,...
                                                  [oo_.exo_steady_state; ...
                                        oo_.exo_det_steady_state], M_.params);
                end
            else
                % linear models
                [fvec,jacob] = feval(fh,dr.ys,[oo_.exo_steady_state;...
                                    oo_.exo_det_steady_state], M_.params);
                if max(abs(fvec)) > 1e-12
                    dr.ys = dr.ys-jacob\fvec;
                end
            end
        end
    end
    % testing for problem
    if check1
        disp('model diagnostic can''t obtain the steady state')
        return
    end

    if ~isreal(dr.ys)
        disp(['model diagnostic obtains a steady state with complex ' ...
              'numbers'])
        return
    end

    %
    % singular Jacobian of static model
    %
    
    [res,jacob]=feval(fh,dr.ys,[dr.ys; oo_.exo_det_steady_state], ...
                      M_.params);
    rank_jacob = rank(jacob);
    if rank_jacob < endo_nbr
        disp(['model_diagnostic: the Jacobian of the static model is ' ...
              'singular'])
        disp(['there is ' num2str(endo_nbr-rank_jacob) ...
              ' colinear relationships between the variables and the equations'])
        ncol = null(jacob);
        n_rel = size(ncol,2);
        for i = 1:n_rel
            if n_rel  > 1
                disp(['Relation ' int2str(i)])
            end
            disp('Colinear variables:')
            for j=1:10
              k = find(abs(ncol(:,i)) > 10^-j);
              if max(abs(jacob(:,k)*ncol(k,i))) < 1e-6
                  break
              end
            end
            disp(endo_names(k,:))
        end
        neq = null(jacob');
        n_rel = size(neq,2);
        for i = 1:n_rel
            if n_rel  > 1
                disp(['Relation ' int2str(i)])
            end
            disp('Colinear equations')
            for j=1:10
              k = find(abs(neq(:,i)) > 10^-j);
              if max(abs(jacob(k,:)'*neq(k,i))) < 1e-6
                  break
              end
            end
            disp(k')
        end
    end