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Computer Arithmetic Package Symbol

Ulp

Ulp[x]
gives the size of an ulp for numbers near x.

To use Ulp, you first need to load the Computer Arithmetic Package using Needs["ComputerArithmetic`"].

The difference between two consecutive machine numbers is called an ulp, which stands for unit in the last place.

The size of an ulp varies depending on where you are in the set of machine numbers. Between 1 and 2 an ulp is equal to $MachineEpsilon, between 2 and 4 an ulp is equal to 2$MachineEpsilon, etc.