Hello,
At the second call of lpx_simplex your problem is primal infeasible so
phase I of the primal simplex is invoked, that is why you see 0 at the
objective value. At iteration 44, it reaches feasibilty and switches
to phase II.
It seems to me that you would like to re-optimize your problem. Is
your problem dual feasible at the second call of lpx_simplex? If so,
you should use dual simplex. Just call lpx_set_int_parm(lp,
LPX_K_DUAL, 1); before lpx_simplex.
Good luck,
Ali
On 6/5/07, Cedric[FR] <[EMAIL PROTECTED]> wrote:
Hi,
In fact, I implement a column generation.
But, when I started again the GLPK simplex, the counter is incrementing.
But I want to initialize my solver by the precedent solution obtained
For example, I obtain:
0: objval = 0.000000000e+00 infeas = 1.000000000e+00 (0)
15: objval = 3.497400000e+04 infeas = 0.000000000e+00 (0)
* 15: objval = 3.497400000e+04 infeas = 0.000000000e+00 (0)
* 29: objval = 2.652371454e+02 infeas = 0.000000000e+00 (0)
OPTIMAL SOLUTION FOUND
29: objval = 0.000000000e+00 infeas = 1.000000000e+00 (0)
44: objval = 3.497400000e+04 infeas = 0.000000000e+00 (0)
* 44: objval = 3.497400000e+04 infeas = 0.000000000e+00 (0)
* 58: objval = 6.586143114e+01 infeas = 0.000000000e+00 (0)
OPTIMAL SOLUTION FOUND
At the second simplex, GLPK starts with an objval=0 instead of the precedent
solution.
Why?
did I use the routine lpx_warm_up?
thanks
Andrew Makhorin wrote:
>
>> How can I save the precedent solution in GLPK?
>
>> In fact, I add a new column at problem. And, I want to initialize my
>> solver by the precedent solution obtained.
>
> Do nothing. The current basis (i.e. the set of row and column statuses)
> is always kept in the problem object.
>
> However, if you then need to re-optimize your instance, make sure that
> before a call to lpx_simplex the lp presolver is disabled.
>
>
>
> _______________________________________________
> Help-glpk mailing list
> [email protected]
> http://lists.gnu.org/mailman/listinfo/help-glpk
>
>
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