If you are using one of the barrier infeasibility algorithms available in the ILOG CPLEX Barrier Optimizer (that is, if you have set BarAlg to either 1 or 2, as discussed later in this chapter), then ILOG CPLEX records an additional column of output titled Inf Ratio, the infeasibility ratio. This ratio, always positive, is a measure of progress for that particular algorithm. In a problem with an optimal solution, you will see this ratio increase to a large number. In contrast, in a problem that is infeasible or unbounded, this ratio will decrease to a very small number.