Error bounds on the solution and a condition estimate are also provided.
If the reciprocal of the condition number is less than machine precision, steps 3 and 4 are skipped. The system of equations is solved for X using the factored form of A. 4. Iterative refinement is applied to improve the computed solution matrix and calculate error bounds and backward error estimates for it. The matrix A will be copied to AF and factored. The factorization has has been completed, but the block diagonal matrix D is exactly singular, so the solution and error bounds could not be computed.