[Help-glpk] CallBacks with PreSolver

[Integral]

Dear Sir,

 

I am using GLPK 3.3 API as a DLL for some Visual Basic 6 applications.

I have implemented a call-back to VB with lib_set_print_hook, which allows to graphically display the opmization progress, by calls to lpx_get_col_info in the VB callback routine.

This works fine. However, when using the presolver, all calls to lpx_get_col_info return 0 as the variable value.

It seems (although I'm not very good in C) that the presolver uses its own internal LPX problem, which is unknown of the API.Callbacks are done by this internal simplex, when my calls to lpx_get_col_info still refer to the original problem...

 

Did I get the problem right?

 

Is there a workaround to this ? (which would not imply too heavy C-code modifications  )

 

Many thanks in advance,

Alain