
180
R.D. Fierro and J.R. Bunch
This shows a large [IH[I translates to a large sin CULY. In the next section we discuss
a way to produce a small IIH[] for the high-rank case k ~ min(m, n). Comparing the a
posteriori bounds for the URV and ULV, we may conclude that the ULV can be expected
to yield a higher quality estimate of the numerical nullspace than the URV. Tables 1-4
summarize the results of some typical experiments that verify this conclusion.
3 THE IMPORTANCE OF A GOOD CONDITION ESTIMATOR
As mentioned earlier, any URV or ULV decomposition may be refined iteratively using