Thread Links Date Links
Thread Prev Thread Next Thread Index Date Prev Date Next Date Index

Re: Motion P1788/M007.01_NaI: Discussion period begins

Arnold Neumaier schrieb:

J. Wolff v. Gudenberg schrieb:

Vincent Lefevre schrieb:



2.2 Arguments

Another argument against NaI: there are different and contradictory
NaI concepts. For instance, if NaI is used for missing data, then
min(some_interval,NaI) should return some_interval, not NaI.


if NaI means illegal construction which is what this motion proposes
it must propagate



"There is an obvious analogy to 754 NaN"

Very partially. NaN can also mean [−∞,+∞] (any real number), as in
hypot(+∞,qNaN), or also the empty set (e.g. result of sqrt(-1)).


The fact that there are different uses for NaI suggest that NaI, if it
is made available, should exist with a payload, so that different uses can be distinguished.
I try to avoid different uses of NaI. I think the only usage of NaI should be "illegal construction". the examples given by Vincent are for NaN not for NaI where we (will) have sqrt(-1) = emptyset hypot(oo,NaI) = NaI. 

to keep our standard simple, I try to avoid the payloads as far as possible.

Juergen



Arnold Neumaier


--
=======
      o          Prof. Dr. J. Wolff v. Gudenberg,  Informatik 2
     / \         Univ. Wuerzburg,  Am Hubland,   D-97074 Wuerzburg
 info2 o        Tel.: +49 931 / 31-86602  Fax: +49 931 / 888-6603
   / \  Uni             e-mail: wolff@xxxxxxxxxxxxxxxxxxxxxxxxxxx
  o   o Wuerzburg         http://www2.informatik.uni-wuerzburg.de/