[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Help-glpk] Problem : basis
From: |
Cedric[FR] |
Subject: |
Re: [Help-glpk] Problem : basis |
Date: |
Thu, 7 Jun 2007 18:35:41 +0400 |
Yes, I delete Rows and Cols
For Row, must I use glp_set_row_stat(lp , i , GLP_NL)?
For Column, must I use glp_set_col_stat(lp , i , GLP_NL)?
How can I fix my column at 0?
must I resolve my problem before to add column or row?
Or
must I only start again the routine lpx_std_basis(lp)?
Andrew Makhorin wrote:
>
>> I tested my example of column generation without the routine
>> lpx_std_basis
>
>> Now, the result is good:
>
>> 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 = 2.652371454e+02 infeas = 0.000000000e+00 (0)
>> * 31: objval = 6.586143114e+01 infeas = 0.000000000e+00 (0)
>> OPTIMAL SOLUTION FOUND
>
>> But, At the 55 st problem, I obtain:
>
>> spx_simplex: initial basis is invalid
>
>> Why? Normally, the precedent solution is feasible
>
>> I don't understand spx_simplex because I don't use. How do I repear
>> the problem? when the lpx_simplex is different of LPX_E_OK
>
> If before changing the problem instance the basis was optimal, you
> do not need to repair it. Probably you changed the status of some
> rows/columns, or deleted some active rows and/or basic columns; this
> invalidates the basis. If you need to delete an active row, just make
> it free; similarly, to delete a basic column it is sufficient to fix
> it at zero.
>
>
>
> _______________________________________________
> Help-glpk mailing list
> address@hidden
> http://lists.gnu.org/mailman/listinfo/help-glpk
>
>
--
View this message in context:
http://www.nabble.com/Problem-%3A-basis-tf3882882.html#a11008669
Sent from the Gnu - GLPK - Help mailing list archive at Nabble.com.