Stable Numerics Subroutine Library
Programming Reference Manual
Version 1.2 DD-00006-012

3.5 Real Triplex Arithmetic TR

Triplex arithmetic TR extends the concept of interval arithmetic IR by incorporating not only the lower bound x and upper bound x, but also an explicit midpoint value x. This midpoint represents the default floating-point value obtained through standard nearest rounding, thereby capturing the central tendency of the interval.

For any triplex number X ∈TR, the relationship between its components is defined as:

x≤x ≤x  ∀X ∈ TR.

This structure allows for a more precise representation of uncertainty or variability, as it explicitly includes the most likely or rounded value alongside the bounds.

3.5.1 Empty Triplex