Editing Moore–Penrose inverse (section)

===Condition number===
Using the pseudoinverse and a [[matrix norm]], one can define a [[condition number]] for any matrix:
<math display="block">\mbox{cond}(A) = \|A\| \left\|A^+\right\|.</math>

A large condition number implies that the problem of finding least-squares solutions to the corresponding system of linear equations is ill-conditioned in the sense that small errors in the entries of {{tmath| A }} can lead to huge errors in the entries of the solution.<ref name=hagen/>