Re: [Help-glpk] Structural variables initial values

[Andrew Makhorin]

Monday, July 16, 2007, 5:14:50 PM, you wrote:

> I upgraded to last version 4.19 but I am expecting lots of toubles using
> functions to modify the problem object..

> That's what:
> 1) I build a MIP problem and solve it (that's fine)
> 2) I add a row and some cols with glp_add_rows() and glp_add_cols()
> 3) I solve the new MIP and I got the expected results
> 4) I revert the MIP back with glp_del_rows() and glp_del_cols()
> 5) I add for the second time a row and few cols
> 6) I try to solve the MIP again but I get the LPX_E_FAULT error. But
> if at this point I save the problem e.g. in the cplex language and
> then try to solve it with glpsol it gives me the correct results!
> Where am I wrong ????

Most probably you delete some active (non-basic) rows and/or basic
columns, so glp_simplex cannot start the search due to invalid basis.
To avoid this error you should call lpx_std_basis or lpx_adv_basis
before glp_simplex.