Question on using FP numbers in python 2

Gene Heskett gheskett at wdtv.com
Sat Feb 15 05:46:17 CET 2014


On Friday 14 February 2014 23:37:53 Chris Angelico did opine:

> On Sat, Feb 15, 2014 at 2:25 PM, Gene Heskett <gheskett at wdtv.com> wrote:
> > Is there something I can search for and fix in some python code that
> > is giving me bogus answers that get good only when there is a valid
> > digit to the left of the decimal point?
> 
> Interesting. I'd look for anything that mixes very large and very
> small numbers, first off. Otherwise, just follow the standard
> debugging technique of stripping code out of your program and seeing
> if the problem's still there. Continue until you have the barest
> minimum, and hope hope hope that it's a Bohr bug and not a Heisenbug!
> 
> If it really is a floating point issue, you probably don't have to
> worry about, for instance, a segfault that happens when a garbage
> collection run occurs between this statement and that statement...
> yes, I've had to deal with that sort of thing! (Turned out to be a
> refcount bug in C code. When the gc ran, something got disposed of
> that shouldn't have.)
> 
> ChrisA

It is the top utility in this page of linuxcnc code generators:

<http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Simple_LinuxCNC_G-
Code_Generators#Counterbore_Software>

I looked at it, just enough to understand I haven't learned a thing in 2 
years of lurking on this list.  I see Big John has a bug note, and its 
possible this might be related.  You can get it at the upper link, or there 
is a copy on my pages, under Genes-os9-stf/LCNC directory.

Cheers, Gene
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page <http://geneslinuxbox.net:6309/gene>

NOTICE: Will pay 100 USD for an HP-4815A defective but
complete probe assembly.




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