log(p1, p2 = v2) public

Returns the natural logarithm of numeric. If additional second argument is given, it will be the base of logarithm.

Math.log(1)          #=> 0.0
Math.log(Math::E)    #=> 1.0
Math.log(Math::E**3) #=> 3.0
Math.log(12,3)       #=> 2.2618595071429146
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July 13, 2009
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Any base logarithm

Using basic arithmetic you can get logarithm with any base:

def log_with_base base, num
  Math.log(num) / Math.log(base)
end

Examples:

>> log_with_base 2, 10
=> 3.32192809488736
>> log_with_base 2, 2
=> 1.0
>> log_with_base 2, 4
=> 2.0
>> log_with_base 2, 16
=> 4.0
>> log_with_base 4, 16
=> 2.0