Entries from 2011-08-12 to 1 day

対数

(1..10).map{|a| 2 ** a}.map{|b| Math::log(b)/Math::log(2) } # => [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0]