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sp组合优化算法的一个改进算法

 SPY COMMAND LINE OPTIONS
 ------------------------


 ./spy [options]

   FORMULA
        -n <numvars>
        -m <numclauses>
        -a <alpha>
        -l <filename>    reads formula from file
   SOLVING
        -B <rate>        backtrack with rate <rate>
        -f <fixes>       per step
        -% <fixes>       per step (%)
        -e <error>       criterion for convergence
        -i <iter>        maximum number of iterations until convergence
        -y <y>           set the inverse pseudo-temperature to y
        -Y               run with runtime optimized pseudo-temperature
        -u <u>           the update rate for Y is set to <u>
        -H               rank the variables according to the average 
			 local field value
   STATS
        -R               replay file
        -F               print fields
        -E               print u-surveys
        -v               increase verbosity (0 to 4)
   MISC
        -s <seed>        (0 = use time, default = 1)
        -/               stop after first convergence
        -h               this help



 FORMULA OPTIONS

 The program either reads an existing formula in conjunctive normal
 form, 

 -l <formula>	loads formula	

 or it generates a new random formula with parameters specified by: 
	
 -n <integer>	number of variables
 -m <integer>	number of clauses
 -a <float>	clause / variable ratio
 -s <integer>	random seed (default 1; 0 use clock)


 SOLVING OPTIONS

 By default we use a pseudo-temperature y = 2 but a different value 
 can be set by

 -y <float>       set the inverse pseudo-temperature
 -Y               run with runtime optimized pseudo-temperature
 -u <integer>     the update rate for Y

 To specify backtracking ratio (default no backtracking) use

 -B <float>        backtrack with a given rate within [0, 0.5]

 Other options are 

 -f <integer>     number of variables fixed per step
 -% <float>       percentage of variables fixed per step (%)
 -e <float>       criterion for convergence
 -i <integer>     maximum number of iterations until convergence
 -H               rank the variables according to the average
                  local field value (experimental)


 OUTPUT

 Five levels of verbosity are available:

 0 (default)	almost no output, just simplification result
 		in output.tmp.out file
 1 (-v)		number of free variables written as progress indicator
                in output.tmp.out file
 2 (-vv)	details about convergence (smileys and dots) 
		in output.tmp.out file and replay.tmp.out file with 
		information about fixing
 3 (-vvv)	list of ALL local fields appended to output.tmp.out file
 4 (-vvvv)	list of ALL local fields and cavity surveys 
		in the output.tmp.out file (use with care, huge output)

 The parameters for verbosity control are: 

 -R 		replay file
 -F             print fields
 -E             print u-surveys
 -v             increase verbosity (0 to 4)
 
 
 MISCELLANEOUS

 -/		stop after first convergence
 -h		print help
 -s <integer>   random seed (default 1; 0 use clock)

 For information about the code see the companion paper downloadable
 from 'www.ictp.trieste.it/~zecchina/SP' or 'cond-mat/0402529'.


 
/*
    Copyright 2004 Demian Battaglia, Alfredo Braunstein, Michal Kolar,
    Michele Leone, Marc Mezard, Martin Weigt and Riccardo Zecchina

    This file is part of SPY (Survey Propagation with finite Y).

    SPY 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 2 of the License, or
    (at your option) any later version.

    SPY 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 SP; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/