function [x, errorflag] = solve1(func, x, j1, j2, jacobian_flag, gstep, tolf, tolx, maxit, fake, debug, varargin)
% Solves systems of non linear equations of several variables
%
% INPUTS
% func: name of the function to be solved
% x: guess values
% j1: equations index for which the model is solved
% j2: unknown variables index
% jacobian_flag=true: jacobian given by the 'func' function
% jacobian_flag=false: jacobian obtained numerically
% gstep increment multiplier in numercial derivative
% computation
% tolf tolerance for residuals
% tolx tolerance for solution variation
% maxit maximum number of iterations
% fake unused argument (compatibity with trust_region).
% debug debug flag
% varargin: list of extra arguments to the function
%
% OUTPUTS
% x: results
% errorflag=1: the model can not be solved
%
% 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 .
nn = length(j1);
g = zeros(nn,1) ;
tolmin = tolx ;
stpmx = 100 ;
errorflag = false ;
fvec = feval(func,x,varargin{:});
fvec = fvec(j1);
idInf = isinf(fvec);
idNan = isnan(fvec);
idCpx = ~isreal(fvec);
if any(idInf)
disp('SOLVE1: during the resolution of the non-linear system, the evaluation of the following equation(s) resulted in a non-finite number:')
disp(j1(idInf)')
errorflag = true;
return
end
if any(idNan)
disp('SOLVE1: during the resolution of the non-linear system, the evaluation of the following equation(s) resulted in a nan:')
disp(j1(idNan)')
errorflag = true;
return
end
if any(idNan)
disp('SOLVE1: during the resolution of the non-linear system, the evaluation of the following equation(s) resulted in a complex number:')
disp(j1(idCpx)')
errorflag = true;
return
end
f = 0.5*(fvec'*fvec);
if max(abs(fvec))