#### Condition Number

Definition.
The condition number of a nonsingular matrix A with respect to a matrix norm is
||A|| ||A-1||.
It is a measure of the sensitivity of the solution of Ax=b to perturbations of A or b.
If the condition number of A is `large', A is said to be ill-conditioned.
If the condition number is near one, A is said to be well-conditioned
If the condition number is one, A is said to be perfectly conditioned.