1 ## Copyright (C) 2002 Etienne Grossmann <etienne@egdn.net>
2 ## Copyright (C) 2009 Levente Torok <TorokLev@gmail.com>
4 ## This program is free software; you can redistribute it and/or modify it under
5 ## the terms of the GNU General Public License as published by the Free Software
6 ## Foundation; either version 3 of the License, or (at your option) any later
9 ## This program is distributed in the hope that it will be useful, but WITHOUT
10 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
14 ## You should have received a copy of the GNU General Public License along with
15 ## this program; if not, see <http://www.gnu.org/licenses/>.
17 ## [a, b, ga, gb, nev] = semi_bracket (f, dx, a, narg, args)
19 ## Find an interval containing a local minimum of the function
20 ## g : h in [a, inf[ ---> f (x+h*dx) where x = args{narg}
22 ## The local minimum may be in a.
24 ## nev is the number of function evaluations.
26 function [a,b,ga,gb,n] = __semi_bracket (f, dx, a, narg, args)
31 args{narg} = x+a*dx; ga = feval (f, args );
33 args{narg} = x+b*dx; gb = feval (f, args );
36 if gb >= ga, return ; end
41 args{narg} = x+c*dx; gc = feval( f, args );
44 if gc >= gb, # ga >= gb <= gc
49 a = b; b = c; ga = gb; gb = gc;