[Bug-glpk] bugs

[massimo scantamburlo]

 

hi andrew. i'm an italian student and for my thesis i'm workig with your glpk. first of all thank you for your work. i think it is a very hard and big one.  i've found some lacks so here they are (i use microsoft VC++ 6.0 under winXP):

 

- in glplpt.c change of maximum lenght for a line form 155 to 1155 (just a big value because i deal with very long constraints)

- in glplpt.c change of maximum lenght for a token image to catch  variables with long name (from 16 to 160)

- i've noticed some wrong behaviours with integer section parsing. i've changed the T_BINARY  define setting to 66 (maybe other likely defines can be wrong but i didn't test them yet)

- the parsing of the model is very sensitive to the blank spaces or line feeds or some data card missing for mps files (Cplex read them all with no problems), too restrictive because it doesn't support definitions like lb<=constraint<=ub .

- many times the solver close with messages like

 

O : lpx_simplex: numerical instability
Assertion failed: spx_check_bbar(lp, lp->tol_bnd) == 0.0; file C:\glpk\glpk-3.2.
2\source\glplpx6a.c; line 701

 

======================================================
B : spx_invert: trying to factorize the basis using threshold tolerance 0.3
spx_invert: trying to factorize the basis using threshold tolerance 0.7
spx_invert: the basis matrix is singular
lpx_simplex: numerical problems with basis matrix
lpx_simplex: sorry, basis recovery procedure not implemented yet
lpx_integer: optimal solution of LP relaxation required
Sorry. Unable to find a start solution. Solver error code: 204.
 Elapsed time 1 (secs)
 Exiting...

======================================================

E: spx_invert: trying to factorize the basis using threshold tolerance 0.3
spx_invert: trying to factorize the basis using threshold tolerance 0.7
spx_invert: the basis matrix is singular
lpx_simplex: numerical problems with basis matrix
lpx_simplex: sorry, basis recovery procedure not implemented yet
lpx_integer: optimal solution of LP relaxation required
Sorry. Unable to find a start solution. Solver error code: 204.
 Elapsed time 36 (secs)
 Exiting...

 

don't you think that could be more helpfull to set an infinite value for no upper or lower bound than setting them to 0 when they are not defined?

i'll tell you everything else i'll find in future. if you already have some updates please make me know. elsewhere i'll try to solve at least the simplest problems. thank you very much.

 

 

Massimo Scantamburlo
address@hidden