Re: [Help-glpk] Problem : basis

[Andrew Makhorin]

> Yes, I delete Rows and Cols

If the current basis is valid (whether optimal or not) and if you
delete active rows (i.e. the rows for which glp_get_row_stat returns
GLP_NL, GLP_NU, GLP_NF, or GLP_NS) and/or basic columns (i.e. the
columns for which glp_get_col_stat returns GLP_BS), the basis becomes
invalid. To keep it valid you either have not to delete such rows or
columns or have to change the statuses of remaining rows and columns
appropriately.

> 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)?

Do you understand what is the row/column status?

> How can I fix my column at 0?

glp_set_col_bnds(lp, j, GLP_FX, 0.0, 0.0);

> must I resolve my problem before to add column or row?

> Or

> must I only start again the routine lpx_std_basis(lp)?

lpx_std_basis makes all auxiliary variables basic and all structural
variables non-basic, i.e. using it you lose all the current basis
information.