dynare/matlab/dynare_solve.m

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function [x, errorflag, fvec, fjac] = dynare_solve(f, x, options, varargin)
% Solves a nonlinear system of equations, f(x) = 0 with n unknowns
% and n equations.
%
% INPUTS
% - f [char, fhandle] function to be solved
% - x [double] n×1 vector, initial guess.
% - options [struct] Dynare options, aka options_.
% - varargin list of additional arguments to be passed to func.
%
% OUTPUTS
% - x [double] n×1 vector, solution.
% - errorflag [logical] scalar, true iff the model can not be solved.
% - fvec [double] n×1 vector, function value at x (f(x), used for debugging when errorflag is true).
% - fjac [double] n×n matrix, Jacobian value at x (J(x), used for debugging when errorflag is true).
%
% REMARKS
% Copyright © 2001-2020 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/>.
jacobian_flag = options.jacobian_flag; % true iff Jacobian is returned by f routine (as a second output argument).
% Set tolerance parameter depending the the caller function.
stack = dbstack;
if isoctave
[~, name, ext]=fileparts(stack(2).file);
caller_file_name=[name,ext];
else
caller_file_name=stack(2).file;
end
if strcmp(caller_file_name,'solve_stacked_problem.m')
tolf = options.dynatol.f;
tolx = options.dynatol.x;
else
tolf = options.solve_tolf;
tolx = options.solve_tolx;
end
if strcmp(caller_file_name,'dyn_ramsey_static.m')
maxit = options.ramsey.maxit;
else
maxit = options.steady.maxit;
end
errorflag = false;
nn = size(x,1);
% Get status of the initial guess (default values?)
if any(x)
% The current initial guess is not the default for all the variables.
idx = find(x); % Indices of the variables with default initial guess values.
in0 = length(idx);
else
% The current initial guess is the default for all the variables.
idx = transpose(1:nn);
in0 = nn;
end
% Get first element of varargin if solve_algo ∈ {12,14} and rename varargin.
if ismember(options.solve_algo, [12, 14])
isloggedlhs = varargin{1};
isauxdiffloggedrhs = varargin{2};
endo_names = varargin{3};
lhs = varargin{4};
arguments = varargin(5:end);
else
arguments = varargin;
end
% checking initial values
if jacobian_flag
[fvec, fjac] = feval(f, x, arguments{:});
wrong_initial_guess_flag = false;
if ~all(isfinite(fvec)) || any(isinf(fjac(:))) || any(isnan((fjac(:)))) ...
|| any(~isreal(fvec)) || any(~isreal(fjac(:)))
if max(abs(fvec)) < tolf %return if initial value solves problem
info = 0;
return;
end
disp('Randomize initial guess...')
% Let's try random numbers for the variables initialized with the default value.
wrong_initial_guess_flag = true;
% First try with positive numbers.
tentative_number = 0;
while wrong_initial_guess_flag && tentative_number<=in0*10
tentative_number = tentative_number+1;
x(idx) = rand(in0, 1)*10;
[fvec, fjac] = feval(f, x, arguments{:});
wrong_initial_guess_flag = ~all(isfinite(fvec)) || any(isinf(fjac(:))) || any(isnan((fjac(:))));
end
% If all previous attempts failed, try with real numbers.
tentative_number = 0;
while wrong_initial_guess_flag && tentative_number<=in0*10
tentative_number = tentative_number+1;
x(idx) = randn(in0, 1)*10;
[fvec, fjac] = feval(f, x, arguments{:});
wrong_initial_guess_flag = ~all(isfinite(fvec)) || any(isinf(fjac(:))) || any(isnan((fjac(:))));
end
% Last tentative, ff all previous attempts failed, try with negative numbers.
tentative_number = 0;
while wrong_initial_guess_flag && tentative_number<=in0*10
tentative_number = tentative_number+1;
x(idx) = -rand(in0, 1)*10;
[fvec, fjac] = feval(f, x, arguments{:});
wrong_initial_guess_flag = ~all(isfinite(fvec)) || any(isinf(fjac(:))) || any(isnan((fjac(:))));
end
end
else
fvec = feval(f, x, arguments{:});
fjac = zeros(nn, nn);
wrong_initial_guess_flag = false;
if ~all(isfinite(fvec))
% Let's try random numbers for the variables initialized with the default value.
wrong_initial_guess_flag = true;
% First try with positive numbers.
tentative_number = 0;
while wrong_initial_guess_flag && tentative_number<=in0*10
tentative_number = tentative_number+1;
x(idx) = rand(in0, 1)*10;
fvec = feval(f, x, arguments{:});
wrong_initial_guess_flag = ~all(isfinite(fvec));
end
% If all previous attempts failed, try with real numbers.
tentative_number = 0;
while wrong_initial_guess_flag && tentative_number<=in0*10
tentative_number = tentative_number+1;
x(idx) = randn(in0, 1)*10;
fvec = feval(f, x, arguments{:});
wrong_initial_guess_flag = ~all(isfinite(fvec));
end
% Last tentative, ff all previous attempts failed, try with negative numbers.
tentative_number = 0;
while wrong_initial_guess_flag && tentative_number<=in0*10
tentative_number = tentative_number+1;
x(idx) = -rand(in0, 1)*10;
fvec = feval(f, x, arguments{:});
wrong_initial_guess_flag = ~all(isfinite(fvec));
end
end
end
% Exit with error if no initial guess has been found.
if wrong_initial_guess_flag
errorflag = true;
x = NaN(size(fvec));
return
end
% this test doesn't check complementarity conditions and is not used for
% mixed complementarity problems
if (~ismember(options.solve_algo,[10,11])) && (max(abs(fvec)) < tolf)
return ;
end
if options.solve_algo == 0
if ~isoctave
if ~user_has_matlab_license('optimization_toolbox')
error('You can''t use solve_algo=0 since you don''t have MATLAB''s Optimization Toolbox')
end
end
options4fsolve=optimset('fsolve');
options4fsolve.MaxFunEvals = 50000;
options4fsolve.MaxIter = maxit;
options4fsolve.TolFun = tolf;
if options.debug==1
options4fsolve.Display = 'final';
else
options4fsolve.Display = 'off';
end
if jacobian_flag
options4fsolve.Jacobian = 'on';
else
options4fsolve.Jacobian = 'off';
end
if ~isoctave
[x, ~, exitval] = fsolve(f, x, options4fsolve, arguments{:});
else
% Under Octave, use a wrapper, since fsolve() does not have a 4th arg
if ischar(f)
f2 = str2func(f);
else
f2 = f;
end
f = @(x) f2(x, arguments{:});
% The Octave version of fsolve does not converge when it starts from the solution
fvec = feval(f, x);
if max(abs(fvec)) >= tolf
[x, ~,exitval] = fsolve(f, x, options4fsolve);
else
exitval = 3;
end
end
if exitval == 1
errorflag = false;
elseif exitval > 1
if ischar(f)
f2 = str2func(f);
else
f2 = f;
end
f = @(x) f2(x, arguments{:});
fvec = feval(f, x);
if max(abs(fvec)) >= tolf
errorflag = true;
else
errorflag = false;
end
else
errorflag = true;
end
elseif options.solve_algo==1
[x, errorflag] = solve1(f, x, 1:nn, 1:nn, jacobian_flag, options.gstep, ...
tolf, tolx, ...
maxit, options.debug, arguments{:});
elseif options.solve_algo==9
[x, errorflag] = trust_region(f, x, 1:nn, 1:nn, jacobian_flag, options.gstep, ...
tolf, tolx, ...
maxit, options.debug, arguments{:});
elseif ismember(options.solve_algo, [2, 12, 4])
if ismember(options.solve_algo, [2, 12])
solver = @solve1;
else
solver = @trust_region;
end
specializedunivariateblocks = options.solve_algo == 12;
if ~jacobian_flag
fjac = zeros(nn,nn) ;
dh = max(abs(x), options.gstep(1)*ones(nn,1))*eps^(1/3);
for j = 1:nn
xdh = x ;
xdh(j) = xdh(j)+dh(j) ;
fjac(:,j) = (feval(f, xdh, arguments{:})-fvec)./dh(j) ;
end
end
[j1,j2,r,s] = dmperm(fjac);
JAC = abs(fjac(j1,j2))>0;
if options.debug
disp(['DYNARE_SOLVE (solve_algo=2|4|12): number of blocks = ' num2str(length(r)-1)]);
end
l = 0;
fre = false;
for i=length(r)-1:-1:1
blocklength = r(i+1)-r(i);
if options.debug
dprintf('DYNARE_SOLVE (solve_algo=2|4|12): solving block %u of size %u.', i, blocklength);
end
j = r(i):r(i+1)-1;
if specializedunivariateblocks
if options.debug
dprintf('DYNARE_SOLVE (solve_algo=2|4|12): solving block %u by evaluating RHS.', i);
end
if isequal(blocklength, 1)
if i<length(r)-1
if fre || any(JAC(r(i), s(i)+(1:l)))
% Reevaluation of the residuals is required because the current RHS depends on
% variables that potentially have been updated previously.
z = feval(f, x, arguments{:});
l = 0;
fre = false;
end
else
% First iteration requires the evaluation of the residuals.
z = feval(f, x, arguments{:});
end
l = l+1;
if isequal(lhs{j1(j)}, endo_names{j2(j)}) || isequal(lhs{j1(j)}, sprintf('log(%s)', endo_names{j2(j)}))
if isloggedlhs(j1(j))
x(j2(j)) = exp(log(x(j2(j)))-z(j1(j)));
else
x(j2(j)) = x(j2(j))-z(j1(j));
end
else
if options.debug
dprintf('LHS variable is not determined by RHS expression (%u).', j1(j))
dprintf('%s -> %s', lhs{j1(j)}, endo_names{j2(j)})
end
if ~isempty(regexp(lhs{j1(j)}, '\<AUX_DIFF_(\d*)\>', 'once'))
if isauxdiffloggedrhs(j1(j))
x(j2(j)) = exp(log(x(j2(j)))+z(j1(j)));
else
x(j2(j)) = x(j2(j))+z(j1(j));
end
else
error('Algorithm solve_algo=%u cannot be used with this nonlinear problem.', options.solve_algo)
end
end
continue
end
else
if options.debug
dprintf('DYNARE_SOLVE (solve_algo=2|4|12): solving block %u with trust_region routine.', i);
end
end
[x, errorflag] = solver(f, x, j1(j), j2(j), jacobian_flag, ...
options.gstep, ...
tolf, options.solve_tolx, ...
maxit, options.debug, arguments{:});
fre = true;
if errorflag
return
end
end
fvec = feval(f, x, arguments{:});
if max(abs(fvec))>tolf
disp('Call solver on the full nonlinear problem.')
[x, errorflag] = solver(f, x, 1:nn, 1:nn, jacobian_flag, ...
options.gstep, tolf, options.solve_tolx, ...
maxit, options.debug, arguments{:});
end
elseif options.solve_algo==3
if jacobian_flag
[x, errorflag] = csolve(f, x, f, 1e-6, 500, arguments{:});
else
[x, errorflag] = csolve(f, x, [], 1e-6, 500, arguments{:});
end
[fvec, fjac] = feval(f, x, arguments{:});
elseif options.solve_algo==10
% LMMCP
olmmcp = options.lmmcp;
[x, ~, exitflag] = lmmcp(f, x, olmmcp.lb, olmmcp.ub, olmmcp, arguments{:});
if exitflag==1
errorflag = false;
else
errorflag = true;
end
elseif options.solve_algo == 11
% PATH mixed complementary problem
% PATH linear mixed complementary problem
if ~exist('mcppath')
error(['PATH can''t be provided with Dynare. You need to install it ' ...
'yourself and add its location to Matlab/Octave path before ' ...
'running Dynare'])
end
omcppath = options.mcppath;
global mcp_data
mcp_data.func = f;
mcp_data.args = arguments;
try
[x, fval, jac, mu] = pathmcp(x,omcppath.lb,omcppath.ub,'mcp_func',omcppath.A,omcppath.b,omcppath.t,omcppath.mu0);
catch
errorflag = true;
end
elseif ismember(options.solve_algo, [13, 14])
if ~jacobian_flag
error('DYNARE_SOLVE: option solve_algo=13|14 needs computed Jacobian')
end
auxstruct = struct();
if options.solve_algo == 14
auxstruct.lhs = lhs;
auxstruct.endo_names = endo_names;
auxstruct.isloggedlhs = isloggedlhs;
auxstruct.isauxdiffloggedrhs = isauxdiffloggedrhs;
end
[x, errorflag] = block_trust_region(f, x, tolf, options.solve_tolx, maxit, options.debug, auxstruct, arguments{:});
[fvec, fjac] = feval(f, x, arguments{:});
else
error('DYNARE_SOLVE: option solve_algo must be one of [0,1,2,3,4,9,10,11,12,13,14]')
end