[AMPL 2555] Knowing Details in Solving Process

[Saber Jalilzadeh-Galaeh]

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Hi all users,

 

I have a MILP model and use CPLEX as a solver.

 

When I want to solve any model in AMPL it gives me some information about branching and optimal solution.

 

Now, I want to have some more additional information about my solution, such as;

Computational time, number of variables and number of constraints and other things.

 

Is it possible to write command/commands to know those which I mentioned above?

 

 

 

Thanks in advance

Saber

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[Matthias-41]

Several built-in ampl parameters can help with this. More are
described in section A.19 of the ampl book and at http://www.ampl.com/FAQ/index.html.

_nvars: number of variables in current model (before presolve)

_ncons: number of constraints in current model (before presolve)

_solve_elapsed_time: total time spent by the solver during the last
solution

You can also use some display options to get cplex to show you more
about the problem. Invoke these by adding them to an "option
cplex_options ..." statement in ampl at some point before solving the
problem. More details are given here:

lpdisplay=1 - cplex gives more details about iterations and elapsed
time as it works

prestats=1 - cplex reports how many variables and constraints it
eliminates during the presolve, and how many are left in the final
problem

timing=1 - cplex reports more details on the time spent during the
solution

Some ampl settings will also show more detail about the problem. More
details on these are given at http://www.ampl.com/NEW/report.html.

option show_stats 1;  - ampl reports how many variables and
constraints are in the problem

option gen_times 1; - ampl reports how much time and memory it uses to
convert your problem into solvable form

option times 1; - ampl reports how much time and memory it uses to
convert your problem into solvable form



On 31 May, 10:21, Saber Jalilzadeh-Galaeh <sbr_612...@...>
wrote:

> Hi all users,
>
> I have a MILP model and use CPLEX as a solver.
>
> When I want to solve any model in AMPL it gives me some information about branching and optimal solution.
>
> Now, I want to have some more additional information about my solution, such as;
> Computational time, number of variables and number of constraints and other things.
>
> Is it possible to write command/commands to know those which I mentioned above?
>
> Thanks in advance
> Saber

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