複數

1i     # => (0+1i)
1.to_c # => (1+0i)
rectangular = Complex(2, 3)  # => (2+3i)
polar       = Complex('1@2') # => (-0.4161468365471424+0.9092974268256817i)

polar.rectangular # => [-0.4161468365471424, 0.9092974268256817]
rectangular.polar # => [3.605551275463989, 0.982793723247329]
rectangular + polar # => (1.5838531634528576+3.909297426825682i)