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Re: More on Exp bugs [message #7659 is a reply to message #7657]

Wed, 18 December 1996 00:00

f055
Messages: 29
Registered: April 1995

Junior Member

-But I didn't like the way I could segfault IDL with just exp() calls.
-(By the way, I STILL can. On a DEC 3000/500 with exp(-90.0) followed by
-exp(-9000.0). (Single precision.) Can anyone else do this?)

Doesn't happen on a DEC 3000/600 with IDL 4.0.

-I realise that this is a MAJOR stir, but I was wondering what people's views
-are on IDL's "NaN" and "Infinity" support?
-Personally: I haven't yet implemented "Infinity" in my IDL programs,
-and I haven't used "NaN" much at all. I like the idea of "NaN", but I
-started many of my programs before it was around in IDL, and so I found other
-ways to cope with "bad values" and the like.

NaN is, I think, a good improvement in dealing with missing data values - but
perhaps only because the previous support was so patchy. But remaining
problems with it are:

1) You can't use it to indicate missing values in integer variables (a
problem if part of a calculation involves integers, even if the start and end
points do not).

2) Many routines still don't have an option to ignore missing values.

3) You cannot write out and read back in NaN data when using ASCII data files.

-I can't be bothered with FP underflows (just give me 0).

Hear hear.

......................... Dr Tim Osborn . t.osborn@uea.ac.uk
.... ___/.. __ /.. /.. /. Senior Research Associate . phone:01603 592089
... /..... /. /.. /.. /.. Climatic Research Unit . fax: 01603 507784
.. /..... __/.. /.. /... School of Environmental Sciences.
. /..... /\ ... /.. /.... University of East Anglia .
____/.._/..\_..____/..... Norwich NR4 7TJ .
......................... UK .

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[Message index]

		Re: More on Exp bugs By: steinhh on Wed, 18 December 1996 00:00
		Re: More on Exp bugs By: f055 on Wed, 18 December 1996 00:00
		Re: More on Exp bugs By: thompson on Mon, 16 December 1996 00:00
		Re: More on Exp bugs By: Peter Mason on Fri, 13 December 1996 00:00

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