SWI-Prolog -- variable_value/3

Documentation
- Reference manual
  - The SWI-Prolog library
    - library(simplex): Solve linear programming problems
      - Introduction
        
        gen_state/1
        
        constraint/3
        
        maximize/3
        
        minimize/3
        
        variable_value/3
        
        objective/2
- Packages

Availability::- use_module(library(simplex)).

variable_value(+State, +Variable, -Value)

Value is unified with the value obtained for Variable. State must correspond to a solved instance.