Before revision:  Built upon a "perturbative" partitioning of the matrix into diagonal and off-diagonal parts, IPT has the complexity of one matrix-vector (when one eigenpair is requested) or one matrix-matrix multiplication (when all eigenpairs are requested) per iteration .
After revision:  Built upon a "perturbative" partitioning of the matrix into diagonal and off-diagonal parts, IPT has the complexity of one matrix-vector or one matrix-matrix multiplication (when all eigenpairs are requested) per iteration .