function [flag,endo_simul,err] = solve_stochastic_perfect_foresight_model(endo_simul,exo_simul,pfm,nnodes,order)

% Copyright (C) 2012-2017 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/>.

flag = 0;
err = 0;
stop = 0;

params = pfm.params;
steady_state = pfm.steady_state;
ny = pfm.ny;
periods = pfm.periods;
dynamic_model = pfm.dynamic_model;
lead_lag_incidence = pfm.lead_lag_incidence;
nyp = pfm.nyp;
nyf = pfm.nyf;
i_cols_1 = pfm.i_cols_1;
i_cols_A1 = pfm.i_cols_A1;
i_cols_j = pfm.i_cols_j;
i_cols_T = nonzeros(lead_lag_incidence(1:2,:)');

maxit = pfm.maxit_;
tolerance = pfm.tolerance;
verbose = pfm.verbose;

number_of_shocks = size(exo_simul,2);

[nodes,weights] = gauss_hermite_weights_and_nodes(nnodes);

if number_of_shocks>1
    nodes = repmat(nodes,1,number_of_shocks)*chol(pfm.Sigma);
    % to be fixed for Sigma ~= I
    for i=1:number_of_shocks
        rr(i) = {nodes(:,i)};
        ww(i) = {weights};
    end
    nodes = cartesian_product_of_sets(rr{:});
    weights = prod(cartesian_product_of_sets(ww{:}),2);
    nnodes = nnodes^number_of_shocks;
else
    nodes = nodes*sqrt(pfm.Sigma);
end

innovations = zeros(periods+2,number_of_shocks);

if verbose
    disp ([' -----------------------------------------------------']);
    disp (['MODEL SIMULATION :']);
    fprintf('\n');
end

z = endo_simul(find(lead_lag_incidence'));
[d1,jacobian] = dynamic_model(z,exo_simul,params,steady_state,2);

% Each column of Y represents a different world
% The upper right cells are unused
% The first row block is ny x 1
% The second row block is ny x nnodes
% The third row block is ny x nnodes^2
% and so on until size ny x nnodes^order
world_nbr = nnodes^order;
Y = repmat(endo_simul(:),1,world_nbr);

% The columns of A map the elements of Y such that
% each block of Y with ny rows are unfolded column wise
dimension = ny*(sum(nnodes.^(0:order-1),2)+(periods-order)*world_nbr);
if order == 0
    i_upd_r = (1:ny*periods);
    i_upd_y = i_upd_r + ny;
else
    i_upd_r = zeros(dimension,1);
    i_upd_y = i_upd_r;
    i_upd_r(1:ny) = (1:ny);
    i_upd_y(1:ny) = ny+(1:ny);
    i1 = ny+1;
    i2 = 2*ny;
    n1 = ny+1;
    n2 = 2*ny;
    for i=2:periods
        k = n1:n2;
        for j=1:nnodes^min(i-1,order)
            i_upd_r(i1:i2) = (n1:n2)+(j-1)*ny*periods;
            i_upd_y(i1:i2) = (n1:n2)+ny+(j-1)*ny*(periods+2);
            i1 = i2+1;
            i2 = i2+ny;
        end
        n1 = n2+1;
        n2 = n2+ny;
    end
end
icA = [find(lead_lag_incidence(1,:)) find(lead_lag_incidence(2,:))+world_nbr*ny ...
       find(lead_lag_incidence(3,:))+2*world_nbr*ny]';
h1 = clock;
for iter = 1:maxit
    h2 = clock;
    A1 = sparse([],[],[],ny*(sum(nnodes.^(0:order-1),2)+1),dimension,(order+1)*world_nbr*nnz(jacobian));
    res = zeros(ny,periods,world_nbr);
    i_rows = 1:ny;
    i_cols = find(lead_lag_incidence');
    i_cols_p = i_cols(1:nyp);
    i_cols_s = i_cols(nyp+(1:ny));
    i_cols_f = i_cols(nyp+ny+(1:nyf));
    i_cols_A = i_cols;
    i_cols_Ap = i_cols_p;
    i_cols_As = i_cols_s;
    i_cols_Af = i_cols_f - ny;
    for i = 1:order+1
        i_w_p = 1;
        for j = 1:nnodes^(i-1)
            innovation = exo_simul;
            if i > 1
                innovation(i+1,:) = nodes(mod(j-1,nnodes)+1,:);
            end
            if i <= order
                for k=1:nnodes
                    y = [Y(i_cols_p,i_w_p);
                         Y(i_cols_s,j);
                         Y(i_cols_f,(j-1)*nnodes+k)];
                    [d1,jacobian] = dynamic_model(y,innovation,params,steady_state,i+1);
                    if i == 1
                        % in first period we don't keep track of
                        % predetermined variables
                        i_cols_A = [i_cols_As - ny; i_cols_Af];
                        A1(i_rows,i_cols_A) = A1(i_rows,i_cols_A) + weights(k)*jacobian(:,i_cols_1);
                    else
                        i_cols_A = [i_cols_Ap; i_cols_As; i_cols_Af];
                        A1(i_rows,i_cols_A) = A1(i_rows,i_cols_A) + weights(k)*jacobian(:,i_cols_j);
                    end
                    res(:,i,j) = res(:,i,j)+weights(k)*d1;
                    i_cols_Af = i_cols_Af + ny;
                end
            else
                y = [Y(i_cols_p,i_w_p);
                     Y(i_cols_s,j);
                     Y(i_cols_f,j)];
                [d1,jacobian] = dynamic_model(y,innovation,params,steady_state,i+1);
                if i == 1
                    % in first period we don't keep track of
                    % predetermined variables
                    i_cols_A = [i_cols_As - ny; i_cols_Af];
                    A1(i_rows,i_cols_A) = jacobian(:,i_cols_1);
                else
                    i_cols_A = [i_cols_Ap; i_cols_As; i_cols_Af];
                    A1(i_rows,i_cols_A) = jacobian(:,i_cols_j);
                end
                res(:,i,j) = d1;
                i_cols_Af = i_cols_Af + ny;
            end
            i_rows = i_rows + ny;
            if mod(j,nnodes) == 0
                i_w_p = i_w_p + 1;
            end
            if i > 1
                if mod(j,nnodes) == 0
                    i_cols_Ap = i_cols_Ap + ny;
                end
                i_cols_As = i_cols_As + ny;
            end
        end
        i_cols_p = i_cols_p + ny;
        i_cols_s = i_cols_s + ny;
        i_cols_f = i_cols_f + ny;
    end
    nzA = cell(periods,world_nbr);
    for j=1:world_nbr
        i_rows_y = find(lead_lag_incidence')+(order+1)*ny;
        offset_c = ny*(sum(nnodes.^(0:order-1),2)+j-1);
        offset_r = (j-1)*ny;
        for i=order+2:periods
            [d1,jacobian] = dynamic_model(Y(i_rows_y,j), ...
                                          exo_simul,params, ...
                                          steady_state,i+1);
            if i == periods
                [ir,ic,v] = find(jacobian(:,i_cols_T));
            else
                [ir,ic,v] = find(jacobian(:,i_cols_j));
            end
            nzA{i,j} = [offset_r+ir,offset_c+icA(ic), v]';
            res(:,i,j) = d1;
            i_rows_y = i_rows_y + ny;
            offset_c = offset_c + world_nbr*ny;
            offset_r = offset_r + world_nbr*ny;
        end
    end
    err = max(abs(res(i_upd_r)));
    if err < tolerance
        stop = 1;
        if verbose
            fprintf('\n') ;
            disp([' Total time of simulation        :' num2str(etime(clock,h1))]) ;
            fprintf('\n') ;
            disp([' Convergency obtained.']) ;
            fprintf('\n') ;
        end
        flag = 0;% Convergency obtained.
        endo_simul = reshape(Y(:,1),ny,periods+2);%Y(ny+(1:ny),1);
                                                  %            figure;plot(Y(16:ny:(periods+2)*ny,:))
                                                  %            pause
        break
    end
    A2 = [nzA{:}]';
    A = [A1; sparse(A2(:,1),A2(:,2),A2(:,3),ny*(periods-order-1)*world_nbr,dimension)];
    dy = -A\res(i_upd_r);
    Y(i_upd_y) =   Y(i_upd_y) + dy;
end

if ~stop
    if verbose
        fprintf('\n') ;
        disp(['     Total time of simulation        :' num2str(etime(clock,h1))]) ;
        fprintf('\n') ;
        disp(['WARNING : maximum number of iterations is reached (modify options_.simul.maxit).']) ;
        fprintf('\n') ;
    end
    flag = 1;% more iterations are needed.
    endo_simul = 1;
end
if verbose
    disp (['-----------------------------------------------------']) ;
end