de Casteljau method for Bézier curve order decrease

de_Casteljau_method.rb

# recursive 'de Casteljau' method. The method multiplies the array's elements in pairs (1st * 2nd, 2nd * 3rd, 3rd * 4th, etc.). Output array is one element less than input array.

# test_ary = [7, 17, 23, 47, 61]

def rec(ary)
        if ary.length == 2 then 
                # base case
                return [ ary[0] * ary[1] ]
        else
                # recursive case
                return [ ary[0] * ary[1] ] + rec(ary[1..-1])
        end
end

# p rec(test_ary)