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Nikos Kazazakis
Nikos Kazazakis
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BARON is having trouble finding a feasible local solution.

The $0.100000E+52$ number is the default number used before the first feasible solution is found.

The word "scaled" can be misleading here, Clp's output hints that your model's constraints are likely overdefined, which causes numerical instability in both the linear and non-linear solvers.

The fact that both solvers have trouble further indicates that the issue is with your linear constraints.

This is typically easily resolved by presolving the problem, although I don't know what linear presolving techniques are implemented in BARON (if any).

If you have access to BARON through AMPL or AIMMS, they will do the linear presolving for you before passing the problem to BARON. Since you are using PYOMO I'm guessing you don't, so your other option would be to try and do some of it yourself - AIMMS have documented the basic algorithms quite nicely.

As a first-order approach, just try the most basic thing first, which is called Singleton reduction. Detect if a variable is fixed (or nearly fixed), remove that variable from your model completely, and substitute it for that number everywhere in the problem. You should also save the number you used because, at the end of the solving process, you'll have to restore the problem to its original dimensionality to retrieve your solution.

BARON is having trouble finding a feasible local solution.

The $0.100000E+52$ number is the default number used before the first feasible solution is found.

The word "scaled" can be misleading here, Clp's output hints that your model's constraints are likely overdefined, which causes numerical instability in both the linear and non-linear solvers.

The fact that both solvers have trouble further indicates that the issue is with your linear constraints.

This is typically easily resolved by presolving the problem, although I don't know what linear presolving techniques are implemented in BARON (if any).

If you have access to BARON through AMPL or AIMMS, they will do the linear presolving for you before passing the problem to BARON. Since you are using PYOMO I'm guessing you don't, so your other option would be to try and do some of it yourself - AIMMS have documented the basic algorithms quite nicely.

As a first-order approach, just try the most basic thing first, which is called Singleton reduction. Detect if a variable is fixed (or nearly fixed), remove that variable from your model completely, and substitute it for that number everywhere in the problem. You should also save the number you used because at the end of the solving process, you'll have to restore the problem to its original dimensionality to retrieve your solution.

BARON is having trouble finding a feasible local solution.

The $0.100000E+52$ number is the default number used before the first feasible solution is found.

The word "scaled" can be misleading here, Clp's output hints that your model's constraints are likely overdefined, which causes numerical instability in both the linear and non-linear solvers.

The fact that both solvers have trouble further indicates that the issue is with your linear constraints.

This is typically easily resolved by presolving the problem, although I don't know what linear presolving techniques are implemented in BARON (if any).

If you have access to BARON through AMPL or AIMMS, they will do the linear presolving for you before passing the problem to BARON. Since you are using PYOMO I'm guessing you don't, so your other option would be to try and do some of it yourself - AIMMS have documented the basic algorithms quite nicely.

As a first-order approach, just try the most basic thing first, which is called Singleton reduction. Detect if a variable is fixed (or nearly fixed), remove that variable from your model completely, and substitute it for that number everywhere in the problem. You should also save the number you used because, at the end of the solving process, you'll have to restore the problem to its original dimensionality to retrieve your solution.

Source Link
Nikos Kazazakis
Nikos Kazazakis
  • 12.3k
  • 18
  • 59

BARON is having trouble finding a feasible local solution.

The $0.100000E+52$ number is the default number used before the first feasible solution is found.

The word "scaled" can be misleading here, Clp's output hints that your model's constraints are likely overdefined, which causes numerical instability in both the linear and non-linear solvers.

The fact that both solvers have trouble further indicates that the issue is with your linear constraints.

This is typically easily resolved by presolving the problem, although I don't know what linear presolving techniques are implemented in BARON (if any).

If you have access to BARON through AMPL or AIMMS, they will do the linear presolving for you before passing the problem to BARON. Since you are using PYOMO I'm guessing you don't, so your other option would be to try and do some of it yourself - AIMMS have documented the basic algorithms quite nicely.

As a first-order approach, just try the most basic thing first, which is called Singleton reduction. Detect if a variable is fixed (or nearly fixed), remove that variable from your model completely, and substitute it for that number everywhere in the problem. You should also save the number you used because at the end of the solving process, you'll have to restore the problem to its original dimensionality to retrieve your solution.