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Contents
module MoreMath
module CantorPairingFunction
module_function
def cantor_pairing(*xs)
if xs.size == 1 and xs.first.respond_to?(:to_ary)
xs = xs.first.to_ary
end
case xs.size
when 0, 1
raise ArgumentError, "at least two arguments are required"
when 2
x, y, = *xs
(x + y) * (x + y + 1) / 2 + y
else
cantor_pairing(cantor_pairing(*xs[0..1]), *xs[2..-1])
end
end
def self.cantor_pairing_inv_f(z)
z * (z + 1) / 2
end
def self.cantor_pairing_inv_q(z)
v = 0
while cantor_pairing_inv_f(v) <= z
v += 1
end
v - 1
end
def cantor_pairing_inv(c, n = 2)
raise ArgumentError, "n is required to be >= 2" unless n >= 2
result = []
begin
q = CantorPairingFunction.cantor_pairing_inv_q(c)
y = c - CantorPairingFunction.cantor_pairing_inv_f(q)
x = q - y
result.unshift y
c = x
n -= 1
end until n <= 1
result.unshift x
end
end
end
Version data entries
11 entries across 11 versions & 1 rubygems