On 9/2/10 Thu Sep 2, 2010 2:00 PM, "Jim" <j...@lowcarbfriends.com> scribbled:
> On 9/2/2010 4:15 PM, Jim Gibson wrote: >> My advice is to stay away from these modules unless you know what you are >> doing. I find that double-precision floating-point arithmetic is always good >> enough. I have been programming in scientific and technical fields for 40 >> years and have yet to need extended-precision arithmentic. >> >> If, on the other hand, you are working with large, financial transactions or >> cryptography, you may need these modules. If that is the case, however, you >> probably shouldn't be looking for help on a Perl beginner's list. >> >> I just do not want anybody to get the impression that these modules are >> needed for accurate arithmetic in Perl and that standard Perl arithmetic >> operations are inaccurate. > > I'm open to more advice. How would you rewrite my original toy code? I wouldn't. It doesn't contain any errors. What you are seeing is the expected behavior. The internal representation of most floating-point numbers is approximate. If you print out binary floating-point numbers at enough precision you will see differences from decimal representations. If you are using double-precision floating-point, the accuracy is about 16 decimal places. If you need more accuracy than that, then you need to use extended precision. But those applications are rare. -- To unsubscribe, e-mail: beginners-unsubscr...@perl.org For additional commands, e-mail: beginners-h...@perl.org http://learn.perl.org/
