277 lines
11 KiB
Prolog
277 lines
11 KiB
Prolog
%%% -*- Mode: Prolog; -*-
|
|
|
|
% This file is part of YAP-LBFGS.
|
|
% Copyright (C) 2009 Bernd Gutmann
|
|
%
|
|
% YAP-LBFGS 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.
|
|
%
|
|
% YAP-LBFGS 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 YAP-LBFGS. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
|
|
|
|
:- module(lbfgs,[optimizer_initialize/3,
|
|
optimizer_initialize/4,
|
|
optimizer_run/2,
|
|
optimizer_get_x/2,
|
|
optimizer_set_x/2,
|
|
|
|
optimizer_get_g/2,
|
|
optimizer_set_g/2,
|
|
|
|
optimizer_finalize/0,
|
|
|
|
optimizer_set_parameter/2,
|
|
optimizer_get_parameter/2,
|
|
optimizer_parameters/0]).
|
|
|
|
% switch on all the checks to reduce bug searching time
|
|
% :- yap_flag(unknown,error).
|
|
% :- style_check(single_var).
|
|
|
|
/**
|
|
|
|
@defgroup YAP-LBFGS
|
|
@ingroup YAPPackages
|
|
|
|
@short What is YAP-LBFGS? YAP-LBFGS is an interface to call libLBFGS, http://www.chokkan.org/software/liblbfgs/, from within
|
|
YAP. libLBFGS is a C library for Limited-memory
|
|
Broyden-Fletcher-Goldfarb-Shanno (L-BFGS) solving the under-constrained
|
|
minimization problem:
|
|
|
|
+ minimize `F(X), X=(x1,x2,..., xN)`
|
|
|
|
|
|
### Contact</h2>
|
|
YAP-LBFGS has been developed by Bernd Gutmann. In case you publish something using YAP-LBFGS, please give credit to me and to libLBFGS. And if you find YAP-LBFGS useful, or if you find a bug, or if you
|
|
port it to another system, ... please send me an email.
|
|
|
|
|
|
### License
|
|
+ YAP-LBFGS 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.
|
|
|
|
+ YAP-LBFGS 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.
|
|
|
|
|
|
### Usage</h2>
|
|
The module lbfgs provides the following predicates after you loaded
|
|
it by
|
|
~~~~
|
|
:-use_module(library(lbfgs)).
|
|
~~~~
|
|
|
|
+ use optimizer_set_paramater(Name,Value) to change parameters
|
|
+ use optimizer_get_parameter(Name,Value) to see current parameters
|
|
+ use optimizer_parameters to print this overview
|
|
|
|
|
|
|
|
### Demo
|
|
|
|
The following Prolog program, ex1.pl, searches for minimas of the
|
|
function `f(x0)=sin(x0)`. In order to do so, it provides the
|
|
call back predicate <span class="code">evaluate` which
|
|
calculates `f(x0)` and the gradient `d/dx0 f=cos(x0)`.
|
|
|
|
~~~~~
|
|
:- use_module(lbfgs).
|
|
|
|
% This is the call back function which evaluates F and the gradient of F
|
|
evaluate(FX,_N,_Step) :-
|
|
optimizer_get_x(0,X0),
|
|
FX is sin(X0),
|
|
G0 is cos(X0),
|
|
optimizer_set_g(0,G0).
|
|
|
|
% This is the call back function which is invoked to report the progress
|
|
% if the last argument is set to anything else than 0, the optimizer will
|
|
% stop right now
|
|
progress(FX,X_Norm,G_Norm,Step,_N,Iteration,Ls,0) :-
|
|
optimizer_get_x(0,X0),
|
|
format('~d. Iteration : x0=~4f f(X)=~4f |X|=~4f
|
|
|X\'|=~4f Step=~4f Ls=~4f~n',
|
|
[Iteration,X0,FX,X_Norm,G_Norm,Step,Ls]).
|
|
|
|
|
|
|
|
demo :-
|
|
format('Optimizing the function f(x0) = sin(x0)~n',[]),
|
|
optimizer_initialize(1,evaluate,progress),
|
|
|
|
|
|
StartX is random*10,
|
|
format('We start the search at the random position x0=~5f~2n',[StartX]),
|
|
optimizer_set_x(0,StartX),
|
|
|
|
optimizer_run(BestF,Status),
|
|
optimizer_get_x(0,BestX0),
|
|
optimizer_finalize,
|
|
format('~2nOptimization done~nWe found a minimum at
|
|
f(~f)=~f~2nLBFGS Status=~w~n',[BestX0,BestF,Status]).
|
|
~~~~~
|
|
The output of this program is something like:
|
|
|
|
~~~~~
|
|
?- demo.
|
|
Optimizing the function f(x0) = sin(x0)
|
|
We start the search at the random position x0=7.24639
|
|
|
|
1. Iteration : x0=5.0167 f(X)=-0.9541 |X|=5.0167 |X'|=0.2996 Step=3.9057 Ls=3.0000
|
|
2. Iteration : x0=4.7708 f(X)=-0.9983 |X|=4.7708 |X'|=0.0584 Step=0.0998 Ls=2.0000
|
|
3. Iteration : x0=4.7113 f(X)=-1.0000 |X|=4.7113 |X'|=0.0011 Step=1.0000 Ls=1.0000
|
|
4. Iteration : x0=4.7124 f(X)=-1.0000 |X|=4.7124 |X'|=0.0000 Step=1.0000 Ls=1.0000
|
|
|
|
|
|
Optimization done
|
|
We found a minimum at f(4.712390)=-1.000000
|
|
|
|
LBFGS Status=0
|
|
yes
|
|
?-
|
|
~~~~~
|
|
|
|
|
|
@{
|
|
|
|
*/
|
|
:- dynamic initialized/0.
|
|
|
|
:- load_foreign_files(['yap_lbfgs'],[],'init_lbfgs_predicates').
|
|
|
|
/** @pred optimizer_initialize(+N,+Evaluate,+Progress)
|
|
The same as before, except that the user module is the default
|
|
value.
|
|
|
|
Example
|
|
~~~~
|
|
optimizer_initialize(1,evaluate,progress)
|
|
~~~~~
|
|
*/
|
|
optimizer_initialize(N,Call_Evaluate,Call_Progress) :-
|
|
optimizer_initialize(N,user,Call_Evaluate,Call_Progress).
|
|
|
|
optimizer_initialize(N,Module,Call_Evaluate,Call_Progress) :-
|
|
optimizer_finalize,
|
|
!,
|
|
optimizer_initialize(N,Module,Call_Evaluate,Call_Progress).
|
|
optimizer_initialize(N,Module,Call_Evaluate,Call_Progress) :-
|
|
\+ initialized,
|
|
|
|
integer(N),
|
|
N>0,
|
|
|
|
% check whether there are such call back functions
|
|
current_module(Module),
|
|
current_predicate(Module:Call_Evaluate/3),
|
|
current_predicate(Module:Call_Progress/8),
|
|
|
|
optimizer_reserve_memory(N),
|
|
|
|
% install call back predicates in the user module which call
|
|
% the predicates given by the arguments
|
|
EvalGoal =.. [Call_Evaluate,E1,E2,E3],
|
|
ProgressGoal =.. [Call_Progress,P1,P2,P3,P4,P5,P6,P7,P8],
|
|
retractall( user:'$lbfgs_callback_evaluate'(_E1,_E2,_E3) ),
|
|
retractall( user:'$lbfgs_callback_progress'(_P1,_P2,_P3,_P4,_P5,_P6,_P7,_P8) ),
|
|
assert( (user:'$lbfgs_callback_evaluate'(E1,E2,E3) :- Module:EvalGoal, !) ),
|
|
assert( (user:'$lbfgs_callback_progress'(P1,P2,P3,P4,P5,P6,P7,P8) :- Module:ProgressGoal, !) ),
|
|
assert(initialized).
|
|
|
|
/** @pred optimizer_finalize/0
|
|
Clean up the memory.
|
|
*/
|
|
optimizer_finalize :-
|
|
initialized,
|
|
optimizer_free_memory,
|
|
retractall(user:'$lbfgs_callback_evaluate'(_,_,_)),
|
|
retractall(user:'$lbfgs_callback_progress'(_,_,_,_,_,_,_,_)),
|
|
retractall(initialized).
|
|
|
|
|
|
/** @pred optimizer_parameters/0
|
|
Prints a table with the current parameters. See the <a href="http://www.chokkan.org/software/liblbfgs/structlbfgs__parameter__t.html#_details">documentation
|
|
of libLBFGS</a> for the meaning of each parameter.
|
|
|
|
~~~~
|
|
?- optimizer_parameters.
|
|
==========================================================================================
|
|
Type Name Value Description
|
|
==========================================================================================
|
|
int m 6 The number of corrections to approximate the inverse hessian matrix.
|
|
float epsilon 1e-05 Epsilon for convergence test.
|
|
int past 0 Distance for delta-based convergence test.
|
|
float delta 1e-05 Delta for convergence test.
|
|
int max_iterations 0 The maximum number of iterations
|
|
int linesearch 0 The line search algorithm.
|
|
int max_linesearch 40 The maximum number of trials for the line search.
|
|
float min_step 1e-20 The minimum step of the line search routine.
|
|
float max_step 1e+20 The maximum step of the line search.
|
|
float ftol 0.0001 A parameter to control the accuracy of the line search routine.
|
|
float gtol 0.9 A parameter to control the accuracy of the line search routine.
|
|
float xtol 1e-16 The machine precision for floating-point values.
|
|
float orthantwise_c 0.0 Coefficient for the L1 norm of variables
|
|
int orthantwise_start 0 Start index for computing the L1 norm of the variables.
|
|
int orthantwise_end -1 End index for computing the L1 norm of the variables.
|
|
==========================================================================================
|
|
~~~~
|
|
*/
|
|
optimizer_parameters :-
|
|
optimizer_get_parameter(m,M),
|
|
optimizer_get_parameter(epsilon,Epsilon),
|
|
optimizer_get_parameter(past,Past),
|
|
optimizer_get_parameter(delta,Delta),
|
|
optimizer_get_parameter(max_iterations,Max_Iterations),
|
|
optimizer_get_parameter(linesearch,Linesearch),
|
|
optimizer_get_parameter(max_linesearch,Max_Linesearch),
|
|
optimizer_get_parameter(min_step,Min_Step),
|
|
optimizer_get_parameter(max_step,Max_Step),
|
|
optimizer_get_parameter(ftol,Ftol),
|
|
optimizer_get_parameter(gtol,Gtol),
|
|
optimizer_get_parameter(xtol,Xtol),
|
|
optimizer_get_parameter(orthantwise_c,Orthantwise_C),
|
|
optimizer_get_parameter(orthantwise_start,Orthantwise_Start),
|
|
optimizer_get_parameter(orthantwise_end,Orthantwise_End),
|
|
|
|
format('/******************************************************************************************~n',[]),
|
|
print_param('Name','Value','Description','Type'),
|
|
format('******************************************************************************************~n',[]),
|
|
print_param(m,M,'The number of corrections to approximate the inverse hessian matrix.',int),
|
|
print_param(epsilon,Epsilon,'Epsilon for convergence test.',float),
|
|
print_param(past,Past,'Distance for delta-based convergence test.',int),
|
|
print_param(delta,Delta,'Delta for convergence test.',float),
|
|
print_param(max_iterations,Max_Iterations,'The maximum number of iterations',int),
|
|
print_param(linesearch,Linesearch,'The line search algorithm.',int),
|
|
print_param(max_linesearch,Max_Linesearch,'The maximum number of trials for the line search.',int),
|
|
print_param(min_step,Min_Step,'The minimum step of the line search routine.',float),
|
|
print_param(max_step,Max_Step,'The maximum step of the line search.',float),
|
|
print_param(ftol,Ftol,'A parameter to control the accuracy of the line search routine.',float),
|
|
print_param(gtol,Gtol,'A parameter to control the accuracy of the line search routine.',float),
|
|
print_param(xtol,Xtol,'The machine precision for floating-point values.',float),
|
|
print_param(orthantwise_c,Orthantwise_C,'Coefficient for the L1 norm of variables',float),
|
|
print_param(orthantwise_start,Orthantwise_Start,'Start index for computing the L1 norm of the variables.',int),
|
|
print_param(orthantwise_end,Orthantwise_End,'End index for computing the L1 norm of the variables.',int),
|
|
format('******************************************************************************************/~n',[]),
|
|
format(' use optimizer_set_paramater(Name,Value) to change parameters~n',[]),
|
|
format(' use optimizer_get_parameter(Name,Value) to see current parameters~n',[]),
|
|
format(' use optimizer_parameters to print this overview~2n',[]).
|
|
|
|
|
|
print_param(Name,Value,Text,Dom) :-
|
|
format(user,'~w~10+~w~19+~w~15+~w~30+~n',[Dom,Name,Value,Text]).
|
|
|
|
|