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## Re: [Help-glpk] [Fwd: Can we set a row with equal upper and lower bound?

**From**: |
Andrew Makhorin |

**Subject**: |
Re: [Help-glpk] [Fwd: Can we set a row with equal upper and lower bound?] |

**Date**: |
Sun, 31 Jul 2011 15:43:29 +0400 |

>* in glp_simplex (glpk-4.45/src/glpapi06.c) you can find the following code:*
>* *
>* if (row->type == GLP_DB && row->lb >= row->ub)*
>* { if (parm->msg_lev >= GLP_MSG_ERR)*
>* xprintf("glp_simplex: row %d: lb = %g, ub = %g; incorrec"*
>* "t bounds\n", i, row->lb, row->ub);*
>* *
>* According to the documentation (doc/glpk.pdf) and to the coding in *
>* routine glp_set_row_bnds() it is allowable for GLP_DB to have lower *
>* bound == upper bound.*
>* *
>* Why would you disallow the the same in glp_simplex?*
Glp_set_row/col_bnds does not check bounds at all; for example, one can
specify a lower bound which is greater than upper one. This is made
intentionally to allow setting lower and upper bounds independently on
each other. However, glp_simplex and other solvers requires all bounds
to be correct.