[VA] "Introducing APRIL !" microchallenge

[J-F Garnier]

ULP = Unit in the Last Place

Sorry, I may have clarified, since I used it a lot, so it's still on-topic.
It's the weight of the last place in a representation of a number in a given system.
Or, in an other way, the minimum change you can do on a number (in a given representation).
It is particularly useful with the BCD (Binary Coded Decimal) representations, although it may be used with binary representations too.
For instance the ULP of the PI representation is 1e-9 on the 41C, 1e-11 on the 71B, and 1e-33 on Free42 (Decimal)
When I used it as in 0.5 ULP, I just used it as a convenient unit. Nothing more complicate.

(04-07-2022 10:59 PM)rprosperi Wrote:  It's interesting to me that in his OP, Valentin commented about how the different machines "...produce very different results when run on said HP calcs".
In these cases, the results differ by about 1E-9. Can that really be considered a very different result, or am I missing something?

I don't want to be Valentin's advocate (he doesn't need), but he wrote:
"... [an] operation that produces a result when executed in one series (...) and a different one when executed in another series (..)".
then later:
"... [an] arithmetic program of mine (...) would produce very different results when run on said HP calcs".
He mentioned in his comment how chaos can exponentially amplify a little perturbation, a well-known, purely deterministic mechanism (when applied to computing).
Seems clear to me (but I may not be the best to judge on this matter :-).

And finally, you may consider that:
- it's a micro-challenge,
- it was posted on April 1st,
- and all this is for fun first !

J-F