| Re: [Offtopic] Re: Strange problem [message #28512 is a reply to message #28394] |
Thu, 06 December 2001 23:57  |
Jeff Hester
Messages: 21
Registered: December 2001
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Junior Member |
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And if you thought that was fun, try the following on for size:
IDL> print,32767+1
The amusing thing is that without even knowing it, your response proves my
point.
We could go on to a discussion of numerical diffusion if somebody wants to
start up a counter (integer, please - 32 bit unsigned) of the number of
brains that explode.
Sorry, but I've really needed a good laugh for a while, and this thread has
provided it. It has even made for some amusing lunch-time conversation.
But all good things must come to an end. Besides, pulling the wings off
flies is not sporting. I should be ashamed.
In all seriousness, if you don't understand why this issue is entirely about
the precision of floating point numbers -- if the problem is not completely
obvious to you -- and if you are trying to actually use IDL to do anything
that anyone will ever care about, however vaguely, then you really should go
and take a basic computing class or two. You are in serious danger of
producing garbage without even being able to recognizing it as such, or
having the slightest clue where it came from. You would not be the first to
announce to the world that you had "discovered" something that turned out to
be nothing more than your own ignorance of the pitfalls of numerical
computing.
My comment about IDL was also serious. IDL is an extraordinarily powerful
tool. I could not easily do what I do without it. But at the same time, it
is a loaded weapon left in an unlocked cabinet.
I'm not sure whether the next line should be, "C'est la vie," "C'est la
guerre," or "O caveat emptor."
Or maybe: you forth love if honk then
(Evidence of a misspent youth.)
Bhautik Joshi wrote:
>> The danger of IDL is that it allows people access to tools about which
>> they have no knowledge.
>> If the fact that floating point representations of numbers have limited
>> precision comes as a
>> shock, one can only wonder...
> As far as I can tell the issue wasn't about limited prescision. Unless
> its a fractional representation, *any* number is going to have a limited
> degree of prescision (whether thats on paper or in the computer) - thats
> something you learn in high school.
>
> The subtle issue of a floating point counter confusing the inequality
> operator in a loop isn't something thats obvious to everybody.
>
>> Is there an emoticon for "shudder in abject fear"?
> No. However, there is an emoticon for when drink international roast
> coffee.
>
> :E
>
> it demonstrates the process of your mouth disentegrating in abject
> objection to the awful aroma that can only be INTERNATIONAL ROAST.
>
> --
> /--------------------------------------------------(__)----- ----\
> | nbj@imag.wsahs.nsw.gov.au | phone: 0404032617 |..|--\ -moo |
> | ICQ #: 2464537 | http://cow.mooh.org | |--| |
> |---------------------------+----------------------\OO/|| ------/
> | international |
> | roast. my sanity has gone |
> | its lost forever |
> \---------------------------/
--
Jeff Hester
Professor
Dept. of Physics & Astronomy
Arizona State University
jhester@asu.edu
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