math.coffee
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module?.exports &&= Math
###*
* @return wheter a Number x, has the same sign as another Number, y.
* @example
* Math.samesign(1,2)
* //-> true
* Math.samesign(-3, 4)
* //-> false
* @test
* Math.samesign(5, 6)
* //-> false
* Math.samesign(-7, -8)
* //-> true
###
Math.samesign = (x, y) -> (x >= 0) != (y < 0)
###*
* @return {Number} a copy of Number x with the same sign of Number y.
* @example
* Math.copysign(1, -2)
* //-> -1
* @test
* Math.copysign(-3, 4)
* //-> 3
* Math.copysign(5, 6)
* //-> 5
* Math.copysign(-7, -8)
* //-> -7
###
Math.copysign = (x, y) -> if Math.samesign x, y then x else -x
###*
* @return {Number} sum of two Numbers.
* @example
* Math.add(1, 2)
* //-> 3
* @test
* Math.add('three', 4)
* //-> NaN
###
Math.add = (a, b) -> (+a) + (+b)
###*
* @return {Number} sum of an Array of Numbers.
* @example
* Math.sum([1, 2, 3])
* //-> 6
###
Math.sum = (nums) -> nums.reduce Math.add
###*
* @return {Number} product of two Numbers.
* @example
* Math.(2, 3)
* //-> 6
###
Math.mul = (a, b) -> a * b
###*
* @return {Number} product of an Array of Numbers.
* @example
* Math.prod(2, 3, 4)
* //-> 24
###
Math.prod = (nums) -> nums.reduce Math.mul
###*
* @return {Number} factorial of a Number.
* @example
* Math.factorial(4)
* //-> 24
* @test
* Math.factorial(3)
* //-> 6
* Math.factorial(2)
* //-> 2
* Math.factorial(1)
* //-> 1
* Math.factorial(0)
* //-> 1
* Math.factorial(-1)
* //-> Infinity
###
Math.factorial = (n) ->
if n < 0 then Infinity
else if n == 0 then 1
else Math.prod.apply null, [1..n]
###*
* Greatest Common Multipler
* @return {Number} greatest common multipler of two Numbers.
* @example
* Math.gcd(493, 289)
* //-> 17
* @test
* Math.gcd(493, -289)
* //-> 17
###
Math.gcd = (a, b) -> [a, b] = [b, a % b] while b; a
###*
* Least Common Multiplier
* @return {Number} least common multiplier of two numbers.
* @example
* Math.lcm(4, 12)
* //-> 12
* @test
* Math.lcm(6, 7)
* //-> 42
###
Math.lcm = (a, b) -> a / Math.gcd(a, b) * b