id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	revision
403	Possible floating point issue in cycle_canceling.h	Alpar Juttner	Peter Kovacs	"From the lemon-devel@lemon.cs.elte.hu mailing list:

   Hello,

   I am using the lemon library 1.2.1 to solve a minCostFlow-problem. I encountered a problem by using the cyclecanceling algorithm. Sometimes, depending on graph and flow settings, the function hangs in an infinity loop at cycle_canceling.h at line 935:
 
   while (mmc.findCycleMean() && mmc.cycleCost() < 0) {

   I do not have deep insight into the algorithm but by debugging I saw that mmc.cycleCost() returns constantly values around -10e-17. Everything seems to work correctly by changing the line to

   while (mmc.findCycleMean() && mmc.cycleCost() < -10e-10) {

   Maybe this is a rounding issue?

   Regards,
   Michael "	defect	closed	major	LEMON 1.3 release	core	hg main	invalid		meistermicha@…