| Ug...Floating Illegal Operand...leave me alone! [message #25786] |
Tue, 17 July 2001 13:05  |
randomguy79
Messages: 1
Registered: July 2001
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Junior Member |
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Hey everyone,
I'm rather new to the world of IDL...so bear with me. I've been
attempting to debug a program all afternoon...but the damn "Program
caused an arithmetic error: Floating illegal operand" message won't go
away no matter what I do. I've narrowed the problem down to an
expression in the following form:
a=a+((b*c)/d) where all the variables are of DOUBLE precision. They
were originally FLOAT but I changed them all and thought it may have
been the problem, but apparently it wasn't.
A little more detail on the program: I'm working through about 73
datasets using a for loop. The expression above is embedded in an
additional for loop so as to perform some manipulations ((b*c)/d) on
arrays and sum all these manipulations into 'a.' The interesting
thing is, I can run 1, 10, or even 72 datasets and not get the
"floating illegal operand" error. Only when I run all 73 datasets at
once do I recieve the message when the program is complete. I'm
getting results as well...I just question whether or not they're right
because of the arithmetic error.
I'm not sure if the Check_math function would help out here or not. I
tried using it earlier but I couldn't actually figure out how to use
it properly. Can anyone help me out here at all? Either helping me
diagnose this or helping me figure out how to use the check_math
function? I'm really stumped and extremely frustrated. Thanks.
Matt
randomguy79@yahoo.com
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| Re: Ug...Floating Illegal Operand...leave me alone! [message #25866 is a reply to message #25786] |
Wed, 18 July 2001 08:55  |
Paul van Delst
Messages: 364
Registered: March 1997
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Senior Member |
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Timm Weitkamp wrote:
>
> Hi,
>
> Concerning Jeff's statement:
>
>> zeros. (I don't think there's a way to make IDL halt at the time the
>> error occurs, as it does with other errors.)
>
> I think that's true, but you can at least make IDL print out the error
> message at the moment where it occurs (instead of the default behavior
> of message output after program termination) by setting the system
> variable !EXCEPT to 2.
Excellent advice for finding those pesky "Floating Illegal Operand" errors. It allowed me
to find where floating underflows in the denominator of an expression were causing rather
largish errors... :o)
Be prepared for a lot of screen output though.
paulv
--
Paul van Delst A little learning is a dangerous thing;
CIMSS @ NOAA/NCEP Drink deep, or taste not the Pierian spring;
Ph: (301)763-8000 x7274 There shallow draughts intoxicate the brain,
Fax:(301)763-8545 And drinking largely sobers us again.
Alexander Pope.
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