After the time required by the ordering algorithm, ILOG CPLEX records information about the Cholesky factor. ILOG CPLEX computes this matrix on each iteration. The number of rows in the Cholesky factor represents the number after preprocessing. The next line of information about the Cholesky factor--integer space required--indicates the amount of memory needed to store the sparsity pattern of the factored matrix. If this number is low, then the factor can be computed more quickly than when the number is high.

Information about the Cholesky factor continues with the number of nonzeros in the factored matrix. The difference between this number and the number of nonzeros in AAT indicates the fill-level of the Cholesky factor.

The final line of information indicates how many floating-point operations are required to compute the Cholesky factor. This number is the best predictor of the relative time that will be required to perform each iteration of the barrier optimizer.