Re: CurrencyConverter not precise
Re: CurrencyConverter not precise
- Subject: Re: CurrencyConverter not precise
- From: Sherm Pendley <email@hidden>
- Date: Fri, 8 Dec 2006 17:27:12 -0500
On Dec 8, 2006, at 4:42 PM, Steffen Börner wrote:
Hi List,
This is my first post here.
I just followed Apples tutorial "Building Currency Converter"
http://developer.apple.com/documentation/Cocoa/Conceptual/
ObjCTutorial/chapter05/chapter_5_section_1.html#//apple_ref/doc/uid/
20002053-TPXREF101
But when entering values with digits after the decimal sign the
calculated amount is not precise.
For example:
Exchange Rate: 3.22
Dollars to Convert: 10
Amount in other Currency:32,20000076293945
In a nutshell, what you've found is a limitation of storing floating-
point numbers in a binary format. Just as 1/3 cannot be exactly
represented as a decimal number, there are numbers that cannot be
exactly represented in binary.
"What Every Computer Scientist Should Know About Floating-point
Arithmetic":
<http://docs.sun.com/source/806-3568/ncg_goldberg.html>
sherm--
Web Hosting by West Virginians, for West Virginians: http://wv-www.net
Cocoa programming in Perl: http://camelbones.sourceforge.net
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