From: Nobuyoshi Nakada <redmine@...>
Date: 2011-01-24T21:12:10+09:00
Subject: [ruby-core:34826] [Ruby 1.9-Bug#4308] Wrong Bignum calculation in some case.

Issue #4308 has been updated by Nobuyoshi Nakada.


#!/usr/bin/env ruby

class Array
  def sum
    reduce(:+)
  end

  def var
    empty? ? 0.0 : (map {|x| x ** 2}.sum * size - sum ** 2).fdiv(size ** 2)
  end
end

# All of these should clearly return 0.

p [1295218865, 1295218865, 1295218865, 1295218865, 1295218865].var
#=> 0.0

p [1295218865, 1295218865, 1295218865, 1295218865, 1295218865, 1295218865].var
#=> 0.0

p [1295218865, 1295218865, 1295218865, 1295218865, 1295218865, 1295218865, 1295218865].var
#=> 0.0

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http://redmine.ruby-lang.org/issues/show/4308

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http://redmine.ruby-lang.org