Bug #3746: Incorrect Float subtraction

• Status: Rejected
• Assignee: -
• Target version: -
• ruby -v: ruby 1.9.2p0 (2010-08-18 revision 29036) [x86_64-linux]

[dim (Dimitrij Denissenko)]

=begin
This is copied from IRB:

ruby-1.9.2-p0 > 2.0 - 1.0
=> 1.0
ruby-1.9.2-p0 > 2.0 - 1.1
=> 0.8999999999999999
ruby-1.9.2-p0 > 2.0 - 1.2
=> 0.8
ruby-1.9.2-p0 > 2.0 - 1.3
=> 0.7
ruby-1.9.2-p0 > 2.0 - 1.4
=> 0.6000000000000001
ruby-1.9.2-p0 > 2.0 - 1.5
=> 0.5
ruby-1.9.2-p0 > 2.0 - 1.6
=> 0.3999999999999999
ruby-1.9.2-p0 > 2.0 - 1.7
=> 0.30000000000000004
ruby-1.9.2-p0 > 2.0 - 1.8
=> 0.19999999999999996
ruby-1.9.2-p0 > 2.0 - 1.9
=> 0.10000000000000009
=end

[naruse (Yui NARUSE)]

• Status changed from Open to Rejected

=begin
Read this.

What Every Computer Scientist Should Know About Floating-Point Arithmetic
http://docs.sun.com/source/806-3568/ncg_goldberg.html
=end

[rogerdpack (Roger Pack)]

=begin
Here's another explanation:

http://wiki.github.com/rdp/ruby_tutorials_core/ruby-talk-faq#floats_imprecise
=end

[kstephens (Kurt Stephens)]

=begin
More explanation:

http://en.wikipedia.org/wiki/Floating_point#Accuracy_problems

Maybe there should be references to these pages in the Float RDOC?

=end

[naruse (Yui NARUSE)]

=begin
I added them.
=end