comp.lang.idl-pvwave archive: archive » Floating underflow in a plot

Home » Public Forums » archive » Floating underflow in a plot

Show: Today's Messages :: Show Polls :: Message Navigator
E-mail to friend

Re: Floating underflow in a plot [message #90777 is a reply to message #90776]

Tue, 14 April 2015 11:28

Heinz Stege
Messages: 189
Registered: January 2003

Senior Member

On Tue, 14 Apr 2015 08:55:05 -0700 (PDT),
miguelfigueirasebastiao@gmail.com wrote:

> El martes, 14 de abril de 2015, 13:36:44 (UTC+2), Heinz Stege escribió:
>> Hi Miguel,
>>
>> there is a system variable named !EXCEPT. You can change its value to
>> !EXCEPT=2. This makes IDL running slower. But the floating underflow
>> message should be accompanied by another message, which tells you the
>> line of the code, where the floating underflow happens.
>>
>> HTH, Heinz
>
> The !EXCEPT=2 is actually in the code (line 4) and the problem arises at the line where oplot is used.
>
Oh, yes, of cause. I was too lazy to look into the code in detail.
Sorry for this.

Seems to be a very strange error. I can't explain it. However, are you
really sure, that the floating underflow error leads to missing
points, as you say in the answer to Craig's post?

You can eliminate the floating-underflow-error by skipping the points
near the position x=0.0 and y=0.0. This can be done be defining
eps=(machar(/double)).eps
somewhere in the head of your code, and replacing the oplot command by
following lines:
x=-sin(!PI-trajectoire(0,*))*trajectoire(1,*)
y=-cos(!PI-trajectoire(0,*))*trajectoire(1,*)
ii=where(abs(x) ge eps and abs(y) ge eps,count)
if count ge 1 then $
oplot,x[ii],y[ii],psym=3,color=fix(inc_color),NSUM=1

This should not make a visible change to your plot. However for me the
plot still looks some kind of "incomplete".

Cheers, Heinz

Report message to a moderator

[Message index]

		Floating underflow in a plot By: Miguel on Tue, 14 April 2015 00:50
		Re: Floating underflow in a plot By: Craig Markwardt on Tue, 14 April 2015 04:32
		Re: Floating underflow in a plot By: Miguel on Tue, 14 April 2015 08:53
		Re: Floating underflow in a plot By: Heinz Stege on Tue, 14 April 2015 04:36
		Re: Floating underflow in a plot By: Miguel on Tue, 14 April 2015 08:55
		Re: Floating underflow in a plot By: Heinz Stege on Tue, 14 April 2015 11:28
		Re: Floating underflow in a plot By: Miguel on Wed, 15 April 2015 10:58
		Re: Floating underflow in a plot By: Jeremy Bailin on Wed, 15 April 2015 12:04
		Re: Floating underflow in a plot By: Lajos Foldy on Tue, 14 April 2015 13:04

Previous Topic:	Regridding NCEP Data
Next Topic:	FG-arithmetic error and moving objects

-=] Back to Top [=-

[ Syndicate this forum (XML) ] [

] [

]

Current Time: Wed Oct 08 16:04:50 PDT 2025

Total time taken to generate the page: 0.00430 seconds