Hi Ralph,
comparisions between NaN and other numbers are not undefined,
here:
http://www.gnu.org/software/libc/manual/html_node/Infinity-and-NaN.html
or
http://stackoverflow.com/questions/1565164/what-is-the-rationale-for-all-comparisons-returning-false-for-ieee754-nan-values
are some remarks on this, quote (from Stackoverflow):
Clause 5.11, paragraph 2 of the 754-2008 standard:
Four mutually exclusive relations are possible: less
than, equal, greater than, and unordered. The last case arises
when at least one operand is NaN. Every NaN shall compare
unordered with everything, including itself.
How DRVL and DRVH behave is a matter of interpretation. If they
are meant to ensure that
DRVL <= value <= DRVH
than it should not be possible to have value==NaN since this is a
contradiction to both relations above.
If they are meant like this:
if DRVL > value:
value= DRVL
if DRVH < value:
value= DRVH
then the record would work as expected, as for NaN both conditions
are false.
Personally I would have expected the first variant.
The possibility to enter "NaN" in panels is at least unexpected. I
wonder what would happen at many EPICS installations if the
operator would take every single entry field and enter "NaN". I
currently wouldn't dare to do this at our facility... ;-)
Greetings
Goetz Pfeiffer
On 11/04/2014 01:41 PM, Ralph Lange wrote: