13.3.1 Fault-tolerant Hardware Features

13.3.2 Fault-tolerant Software Features

Fault tolerance can be simulated in software. One example of such a technique is the sequence

                           
 ensure|x2 - y |< tolerable
 by x := SqrtA(y)
 else x := SqrtB(y)
 else error
 

Here, multiple versions of a function which computes a square root are provided, increasing the likelihood that the square root value returned satisfies some criterion.