[shoo]

related: there is a short series of exercises in SICP that explore the idea of building an interval arithmetic library. i.e. numerical values are represented by intervals [a, b] which encode their uncertainty/error:

http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-14.html...

Exercise 2.14 and onwards point out that two expressions that are algebraically equivalent for perfectly accurate values stop being equivalent once we introduce uncertainty. This is only for a toy example expression with 2 variables. Suppose we want to solve a linear system of equations in 100s of thousands of variables. Is it tractable to track the uncertainty for all of those variables at once? Will their uncertainties be dependent? ...

[ronaldx]

aye, this matches my intuition: having a lower bound and an upper bound (as rational numbers) on each value means you can:

- go back and improve if necessary, or otherwise - express the uncertainty of a comparison

thanks for the link :)

[GhotiFish]

... that is a really good idea. Why do I keep putting off reading that book?!