Syntactic Confectionery Delight PerlMonks

### Re^3: Is this odd behavior a floating point problem?

by davido (Archbishop)
 on Mar 23, 2012 at 18:09 UTC ( #961274=note: print w/replies, xml ) Need Help??

It's not a Perl problem, it's the problem of representing a non-terminating series for base 2 using a finite number of binary digits. You are accustomed to seeing it in base ten when you try to represent 1/3rd, yet I hear no complaints that your ten counting fingers are malfunctioning. Your calculator gets it right by rounding to the eight or ten significant digits that you see on its little LCD display. In other words, it really doesn't get it right; it just covers up the ugliness. And, in fact, I see a nearly identical question every day in reference to C, C++, PHP, and myriad other programming languages over on StackOverflow. It's not a problem unique to Perl.

I understand that the "What every computer scientist should know..." article is a little beyond what someone who just wants to get the job done might want to digest. That's fine, the article goes into painful details. Try this response (shameless plug, I wrote it), which tries to spell it out in less technical terms: Re: shocking imprecision.

Dave

• Comment on Re^3: Is this odd behavior a floating point problem?

Create A New User
Node Status?
node history
Node Type: note [id://961274]
help
Chatterbox?
 [thezip]: G'day all! [perldigious]: Well, that and dodging the people who forget how ice works right away. :-) [stevieb]: hey, thezip [perldigious]: I don't miss having to drive up and down in elevation on roads that are iced over, I white knuckled gripping the steering wheel every time I had to where I used to live. [perldigious]: So I don't envy you mountain guys if you have to drive in the winter, even with tire chains. MidLifeXis waves. [stevieb]: man, I absolutely LOVE driving in the worst winter conditions. In the mountainous roads, there are extremely few (if any) other drivers. I love the challenge. I've been doing extreme off-road my whole life, and as I said, I'm always well... [stevieb]: ...prepared for even the very worst Discipulus seems a part of the globe very unfrindly with Kawasaki riders..

How do I use this? | Other CB clients
Other Users?
Others taking refuge in the Monastery: (13)
As of 2016-12-06 16:46 GMT
Sections?
Information?
Find Nodes?
Leftovers?
Voting Booth?
On a regular basis, I'm most likely to spy upon:

Results (112 votes). Check out past polls.