ColgenInstance:get(++What, -Value)

What

Specification for information wanted (atom)

Value

Returned value of What

Description

Retrieve information about solver constraints and results, for the colgen instance ColgenInstance. What can take one of the following values:

dual(+Id)

Returns the floating-point value of the current dual value for the constraint having identifier Id. See also sp_obj below.

sp_obj(+Id)

Returns the sub problem objective terms currently associated associated with the constraint having identifier Id. This will be a term Val*Var where Val is the current dual value for the constraint as also returned by ColgenInstance:get(dual(Id), Val) and Var is the subproblem variable in the implicit sum term of the constraint. It is the users responsibility to get all relevant terms of the current cost function and ensure that subproblem solutions posted to the colgen instance have a non-negative cost.

vars

Returns a list of all variables currently associated with the colgen instance ColgenInstance.

non_zero_vars

Returns a list of all variables currently associated with the colgen instance ColgenInstance that have a non-zero optimal solution. This may be more efficient than retrieving all problem variables after solution, since very many variables can be generated and most will have a zero value in the optimal solution.

frac_vars

Returns a list of all variables currently associated with the colgen instance ColgenInstance that have a fractional optimal solution. This is intended for use primarily in user-defined problem branching predicates.

column_count

Number of generated columns.

obj_val

Current objective value.

unsatisfiable_cstrs

satisfiable_cstrs

generated_non_zero_vars

non_zero_vars

vars

sep_goal

Separation goal.

sp_solver

Subproblem solver goal.

stab_coeff/bound_minus/plus(Ident)

Stabilisation parameters per constraint.