Bug #10592: Adding floats resluts in an incorrect result

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: ruby 2.1.5p273 (2014-11-13 revision 48405) [x86_64-linux]
• Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN

[doma (Domokos Molnar)]

1.1+1.1+1.1 = 3.3

However in the current 2.1.5 this is what happens:

dmolnar@domalaptop:~> irb
2.1.5 :001 > 1.1+1.1+1.1
 => 3.3000000000000003 
2.1.5 :002 >

[doma (Domokos Molnar)]

dmolnar@domalaptop:~> irb
2.1.5 :001 > 1.1+1.1+1.1-3.3
 => 4.440892098500626e-16 

[recursive-madman (Recursive Madman)]

This is not a ruby bug. See http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems

[recursive-madman (Recursive Madman)]

Use Rational if you want exact results:

1.1 * 3 #=> 3.3000000000000003

(Rational('1.1') * 3).to_f #=> 3.3

[nobu (Nobuyoshi Nakada)]

• Description updated (diff)
• Status changed from Open to Rejected

[doma (Domokos Molnar)]

So true. Sorry about reporting it.