the meaning of AMPL output

[Yasin053]

Hi,
I was wondering if someone can explain me the meaning of the below AMPL
output.
Even though it states that the problem is infeasible, it provides the values
of the variables as well as the objective function value. Also, it is weird
that no violated constraint is provided.
Thanks,

CPLEX 11.2.0: infeasible problem.
6 dual simplex iterations (0 in phase I)
constraint.dunbdd returned

suffix dunbdd OUT;
dual_var :=
1 72559415 0 3.33333
1 145118825 0 0
1 217678235 0 0
1 290237645 0 1.66667
2 3922632452 0 2.85714
2 7845264902 0 0
2 11767897352 0 0
2 15690529802 0 0
2 19613162252 0 0
2 23535794702 0 0
2 27458427152 0 0
2 31381059602 0 2.14286
3 72559414 0 6.25
3 145118824 0 0
3 217678234 0 0
3 290237644 0 0
3 362797054 0 -1.25
;

total_value = 2450
--
View this message in context: http://old.nabble.com/the-meaning-of-AMPL-output-tp29378176p29378176.html
Sent from the AMPL mailing list archive at Nabble.com.

[Paul]

On Aug 7, 11:22 pm, Yasin053 <yasin...@gmail.com> wrote:
> Hi,
> I was wondering if someone can explain me the meaning of the below AMPL
> output.
> Even though it states that the problem is infeasible, it provides the values
> of the variables as well as the objective function value. Also, it is weird
> that no violated constraint is provided.
> Thanks,
>
> CPLEX 11.2.0: infeasible problem.

The *primal* problem is infeasible.

> 6 dual simplex iterations (0 in phase I)
> constraint.dunbdd returned
>
> suffix dunbdd OUT;

This gives the last found solution to the *dual* problem. An
infeasible primal usually has an unbounded dual. I'm not sure if this
is a vertex of the dual feasible region or a recession direction (the
direction of an unbounded ray), but I would guess vertex.

> dual_var :=
> 1 72559415    0    3.33333
> 1 145118825   0    0
> 1 217678235   0    0
> 1 290237645   0    1.66667
> 2 3922632452  0    2.85714
> 2 7845264902  0    0
> 2 11767897352 0    0
> 2 15690529802 0    0
> 2 19613162252 0    0
> 2 23535794702 0    0
> 2 27458427152 0    0
> 2 31381059602 0    2.14286
> 3 72559414    0    6.25
> 3 145118824   0    0
> 3 217678234   0    0
> 3 290237644   0    0
> 3 362797054   0   -1.25
> ;
>
> total_value = 2450

/Paul