Re: P1788.1/M001.01
On Fri, 25 Sep 2015 01:56:29 +0330, Mehran Mazandarani wrote:
> However, the result does not show the possible values
> if they correspond to a same source.
Ah yes, this is the famous *dependency* issue. In general we don't know
whether x and y in f(x,y) are two names for the "same thing", or are two
independent things whose values as intervals may happen to be the same.
Moore's arithmetic is indeed a worst-case arithmetic -- but this allows
it to *guarantee* that the computed result encloses any possible actual
result.
When an interval programmer writes a program to compute a particular
function, which could (in the point-function context) be written as an
algebraic expression where certain variables may appear multiple times,
the programmer may take advantage of specific knowledge -- in particular,
monotonicity properties -- to compute a tighter enclosure than blindly
evaluating the expression using Moore arithmetic.
See Chapter 6 in the full IEEE Std 1788-2015.
Michel.
---Sent: 2015-09-24 22:43:51 UTC