217 lines
6.9 KiB
Matlab
217 lines
6.9 KiB
Matlab
function [fhat,xhat,fcount,retcode] = csminit(fcn,x0,f0,g0,badg,H0,varargin)
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% [fhat,xhat,fcount,retcode] = csminit(fcn,x0,f0,g0,badg,H0,...
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% P1,P2,P3,P4,P5,P6,P7,P8)
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% retcodes: 0, normal step. 5, largest step still improves too fast.
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% 4,2 back and forth adjustment of stepsize didn't finish. 3, smallest
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% stepsize still improves too slow. 6, no improvement found. 1, zero
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% gradient.
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%---------------------
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% Modified 7/22/96 to omit variable-length P list, for efficiency and compilation.
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% Places where the number of P's need to be altered or the code could be returned to
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% its old form are marked with ARGLIST comments.
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%
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% Fixed 7/17/93 to use inverse-hessian instead of hessian itself in bfgs
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% update.
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%
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% Fixed 7/19/93 to flip eigenvalues of H to get better performance when
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% it's not psd.
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%
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% Fixed 02/19/05 to correct for low angle problems.
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%
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%tailstr = ')';
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%for i=nargin-6:-1:1
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% tailstr=[ ',P' num2str(i) tailstr];
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%end
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% Copyright (C) 1993-2011 Tao Zha and Christopher Sims
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%
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% This file is part of Dynare.
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%
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% Dynare is free software: you can redistribute it and/or modify
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% it under the terms of the GNU General Public License as published by
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% the Free Software Foundation, either version 3 of the License, or
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% (at your option) any later version.
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%
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% Dynare is distributed in the hope that it will be useful,
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% but WITHOUT ANY WARRANTY; without even the implied warranty of
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% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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% GNU General Public License for more details.
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%
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% You should have received a copy of the GNU General Public License
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% along with Dynare. If not, see <http://www.gnu.org/licenses/>.
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dispIndx = 0; % 1: turn on all the diplays on the screen; 0: turn off (Added by T. Zha)
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%ANGLE = .03; % when output of this variable becomes negative, we have wrong analytical graident
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ANGLE = .005; % works for identified VARs and OLS
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%THETA = .03;
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THETA = .3; %(0<THETA<.5) THETA near .5 makes long line searches, possibly fewer iterations.
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FCHANGE = 1000;
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MINLAMB = 1e-9;
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% fixed 7/15/94
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% MINDX = .0001;
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% MINDX = 1e-6;
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MINDFAC = .01;
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fcount=0;
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lambda=1;
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xhat=x0;
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f=f0;
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fhat=f0;
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g = g0;
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gnorm = norm(g);
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%
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if (gnorm < 1.e-12) && ~badg % put ~badg 8/4/94
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retcode =1;
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dxnorm=0;
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% gradient convergence
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else
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% with badg true, we don't try to match rate of improvement to directional
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% derivative. We're satisfied just to get some improvement in f.
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%
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%if(badg)
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% dx = -g*FCHANGE/(gnorm*gnorm);
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% dxnorm = norm(dx);
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% if dxnorm > 1e12
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% disp('Bad, small gradient problem.')
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% dx = dx*FCHANGE/dxnorm;
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% end
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%else
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% Gauss-Newton step;
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%---------- Start of 7/19/93 mod ---------------
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%[v d] = eig(H0);
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%toc
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%d=max(1e-10,abs(diag(d)));
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%d=abs(diag(d));
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%dx = -(v.*(ones(size(v,1),1)*d'))*(v'*g);
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% toc
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dx = -H0*g;
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% toc
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dxnorm = norm(dx);
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if dxnorm > 1e12
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if dispIndx, disp('Near-singular H problem.'), end
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dx = dx*FCHANGE/dxnorm;
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end
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dfhat = dx'*g0;
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%end
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%
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%
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if ~badg
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% test for alignment of dx with gradient and fix if necessary
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a = -dfhat/(gnorm*dxnorm);
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if a<ANGLE
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dx = dx - (ANGLE*dxnorm/gnorm+dfhat/(gnorm*gnorm))*g;
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% suggested alternate code: ---------------------
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dx = dx*dxnorm/norm(dx); % Added 02/19/05 by CAS. This keeps scale invariant to the angle correction
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% ------------------------------------------------
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dfhat = dx'*g;
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% dxnorm = norm(dx); % Removed 02/19/05 by CAS. This line unnecessary with modification that keeps scale invariant
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if dispIndx, disp(sprintf('Correct for low angle: %g',a)), end
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end
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end
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if dispIndx, disp(sprintf('Predicted improvement: %18.9f',-dfhat/2)), end
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%
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% Have OK dx, now adjust length of step (lambda) until min and
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% max improvement rate criteria are met.
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done=0;
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factor=3;
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shrink=1;
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lambdaMin=0;
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lambdaMax=inf;
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lambdaPeak=0;
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fPeak=f0;
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lambdahat=0;
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while ~done
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if size(x0,2)>1
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dxtest=x0+dx'*lambda;
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else
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dxtest=x0+dx*lambda;
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end
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% home
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f = feval(fcn,dxtest,varargin{:});
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%ARGLIST
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%f = feval(fcn,dxtest,P1,P2,P3,P4,P5,P6,P7,P8,P9,P10,P11,P12,P13);
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% f = feval(fcn,x0+dx*lambda,P1,P2,P3,P4,P5,P6,P7,P8);
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if dispIndx, disp(sprintf('lambda = %10.5g; f = %20.7f',lambda,f )), end
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%debug
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%disp(sprintf('Improvement too great? f0-f: %g, criterion: %g',f0-f,-(1-THETA)*dfhat*lambda))
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if f<fhat
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fhat=f;
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xhat=dxtest;
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lambdahat = lambda;
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end
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fcount=fcount+1;
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shrinkSignal = (~badg & (f0-f < max([-THETA*dfhat*lambda 0]))) | (badg & (f0-f) < 0) ;
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growSignal = ~badg & ( (lambda > 0) & (f0-f > -(1-THETA)*dfhat*lambda) );
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if shrinkSignal && ( (lambda>lambdaPeak) || (lambda<0) )
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if (lambda>0) && ((~shrink) || (lambda/factor <= lambdaPeak))
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shrink=1;
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factor=factor^.6;
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while lambda/factor <= lambdaPeak
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factor=factor^.6;
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end
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%if (abs(lambda)*(factor-1)*dxnorm < MINDX) || (abs(lambda)*(factor-1) < MINLAMB)
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if abs(factor-1)<MINDFAC
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if abs(lambda)<4
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retcode=2;
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else
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retcode=7;
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end
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done=1;
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end
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end
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if (lambda<lambdaMax) && (lambda>lambdaPeak)
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lambdaMax=lambda;
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end
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lambda=lambda/factor;
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if abs(lambda) < MINLAMB
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if (lambda > 0) && (f0 <= fhat)
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% try going against gradient, which may be inaccurate
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if dispIndx, lambda = -lambda*factor^6, end
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else
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if lambda < 0
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retcode = 6;
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else
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retcode = 3;
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end
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done = 1;
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end
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end
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elseif (growSignal && lambda>0) || (shrinkSignal && ((lambda <= lambdaPeak) && (lambda>0)))
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if shrink
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shrink=0;
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factor = factor^.6;
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%if ( abs(lambda)*(factor-1)*dxnorm< MINDX ) || ( abs(lambda)*(factor-1)< MINLAMB)
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if abs(factor-1)<MINDFAC
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if abs(lambda)<4
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retcode=4;
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else
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retcode=7;
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end
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done=1;
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end
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end
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if ( f<fPeak ) && (lambda>0)
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fPeak=f;
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lambdaPeak=lambda;
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if lambdaMax<=lambdaPeak
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lambdaMax=lambdaPeak*factor*factor;
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end
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end
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lambda=lambda*factor;
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if abs(lambda) > 1e20;
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retcode = 5;
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done =1;
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end
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else
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done=1;
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if factor < 1.2
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retcode=7;
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else
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retcode=0;
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end
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end
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end
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end
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if dispIndx, disp(sprintf('Norm of dx %10.5g', dxnorm)), end
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