# <!-- rdoc-file=complex.c -->
# A Complex object houses a pair of values, given when the object is created as
# either *rectangular coordinates* or *polar coordinates*.
#
# ## Rectangular Coordinates
#
# The rectangular coordinates of a complex number are called the *real* and
# *imaginary* parts; see [Complex number
# definition](https://en.wikipedia.org/wiki/Complex_number#Definition).
#
# You can create a Complex object from rectangular coordinates with:
#
# *   A [complex literal](rdoc-ref:doc/syntax/literals.rdoc@Complex+Literals).
# *   Method Complex.rect.
# *   Method Kernel#Complex, either with numeric arguments or with certain
#     string arguments.
# *   Method String#to_c, for certain strings.
#
#
# Note that each of the stored parts may be a an instance one of the classes
# Complex, Float, Integer, or Rational; they may be retrieved:
#
# *   Separately, with methods Complex#real and Complex#imaginary.
# *   Together, with method Complex#rect.
#
#
# The corresponding (computed) polar values may be retrieved:
#
# *   Separately, with methods Complex#abs and Complex#arg.
# *   Together, with method Complex#polar.
#
#
# ## Polar Coordinates
#
# The polar coordinates of a complex number are called the *absolute* and
# *argument* parts; see [Complex polar
# plane](https://en.wikipedia.org/wiki/Complex_number#Polar_complex_plane).
#
# In this class, the argument part in expressed
# [radians](https://en.wikipedia.org/wiki/Radian) (not
# [degrees](https://en.wikipedia.org/wiki/Degree_(angle))).
#
# You can create a Complex object from polar coordinates with:
#
# *   Method Complex.polar.
# *   Method Kernel#Complex, with certain string arguments.
# *   Method String#to_c, for certain strings.
#
#
# Note that each of the stored parts may be a an instance one of the classes
# Complex, Float, Integer, or Rational; they may be retrieved:
#
# *   Separately, with methods Complex#abs and Complex#arg.
# *   Together, with method Complex#polar.
#
#
# The corresponding (computed) rectangular values may be retrieved:
#
# *   Separately, with methods Complex#real and Complex#imag.
# *   Together, with method Complex#rect.
#
class Complex < Numeric
  # <!--
  #   rdoc-file=complex.c
  #   - Complex.polar(abs, arg = 0) -> complex
  # -->
  # Returns a new Complex object formed from the arguments, each of which must be
  # an instance of Numeric, or an instance of one of its subclasses: Complex,
  # Float, Integer, Rational. Argument `arg` is given in radians; see [Polar
  # Coordinates](rdoc-ref:Complex@Polar+Coordinates):
  #
  #     Complex.polar(3)        # => (3+0i)
  #     Complex.polar(3, 2.0)   # => (-1.2484405096414273+2.727892280477045i)
  #     Complex.polar(-3, -2.0) # => (1.2484405096414273+2.727892280477045i)
  #
  def self.polar: (Numeric, ?Numeric) -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - Complex.rect(real, imag = 0) -> complex
  # -->
  # Returns a new Complex object formed from the arguments, each of which must be
  # an instance of Numeric, or an instance of one of its subclasses: Complex,
  # Float, Integer, Rational; see [Rectangular
  # Coordinates](rdoc-ref:Complex@Rectangular+Coordinates):
  #
  #     Complex.rect(3)             # => (3+0i)
  #     Complex.rect(3, Math::PI)   # => (3+3.141592653589793i)
  #     Complex.rect(-3, -Math::PI) # => (-3-3.141592653589793i)
  #
  # Complex.rectangular is an alias for Complex.rect.
  #
  def self.rect: (Numeric, ?Numeric) -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - Complex.rect(real, imag = 0) -> complex
  # -->
  # Returns a new Complex object formed from the arguments, each of which must be
  # an instance of Numeric, or an instance of one of its subclasses: Complex,
  # Float, Integer, Rational; see [Rectangular
  # Coordinates](rdoc-ref:Complex@Rectangular+Coordinates):
  #
  #     Complex.rect(3)             # => (3+0i)
  #     Complex.rect(3, Math::PI)   # => (3+3.141592653589793i)
  #     Complex.rect(-3, -Math::PI) # => (-3-3.141592653589793i)
  #
  # Complex.rectangular is an alias for Complex.rect.
  #
  alias self.rectangular self.rect

  # <!--
  #   rdoc-file=complex.c
  #   - complex * numeric -> new_complex
  # -->
  # Returns the product of `self` and `numeric`:
  #
  #     Complex(2, 3)  * Complex(2, 3)  # => (-5+12i)
  #     Complex(900)   * Complex(1)     # => (900+0i)
  #     Complex(-2, 9) * Complex(-9, 2) # => (0-85i)
  #     Complex(9, 8)  * 4              # => (36+32i)
  #     Complex(20, 9) * 9.8            # => (196.0+88.2i)
  #
  def *: (Numeric) -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - complex ** numeric -> new_complex
  # -->
  # Returns `self` raised to power `numeric`:
  #
  #     Complex('i') ** 2             # => (-1+0i)
  #     Complex(-8) ** Rational(1, 3) # => (1.0000000000000002+1.7320508075688772i)
  #
  def **: (Numeric) -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - complex + numeric -> new_complex
  # -->
  # Returns the sum of `self` and `numeric`:
  #
  #     Complex(2, 3)  + Complex(2, 3)  # => (4+6i)
  #     Complex(900)   + Complex(1)     # => (901+0i)
  #     Complex(-2, 9) + Complex(-9, 2) # => (-11+11i)
  #     Complex(9, 8)  + 4              # => (13+8i)
  #     Complex(20, 9) + 9.8            # => (29.8+9i)
  #
  def +: (Numeric) -> Complex

  def +@: () -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - complex - numeric -> new_complex
  # -->
  # Returns the difference of `self` and `numeric`:
  #
  #     Complex(2, 3)  - Complex(2, 3)  # => (0+0i)
  #     Complex(900)   - Complex(1)     # => (899+0i)
  #     Complex(-2, 9) - Complex(-9, 2) # => (7+7i)
  #     Complex(9, 8)  - 4              # => (5+8i)
  #     Complex(20, 9) - 9.8            # => (10.2+9i)
  #
  def -: (Numeric) -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - -complex -> new_complex
  # -->
  # Returns the negation of `self`, which is the negation of each of its parts:
  #
  #     -Complex(1, 2)   # => (-1-2i)
  #     -Complex(-1, -2) # => (1+2i)
  #
  def -@: () -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - complex / numeric -> new_complex
  # -->
  # Returns the quotient of `self` and `numeric`:
  #
  #     Complex(2, 3)  / Complex(2, 3)  # => ((1/1)+(0/1)*i)
  #     Complex(900)   / Complex(1)     # => ((900/1)+(0/1)*i)
  #     Complex(-2, 9) / Complex(-9, 2) # => ((36/85)-(77/85)*i)
  #     Complex(9, 8)  / 4              # => ((9/4)+(2/1)*i)
  #     Complex(20, 9) / 9.8            # => (2.0408163265306123+0.9183673469387754i)
  #
  def /: (Numeric) -> Complex

  def <: (Numeric) -> bot

  def <=: (Numeric) -> bot

  # <!--
  #   rdoc-file=complex.c
  #   - complex <=> object -> -1, 0, 1, or nil
  # -->
  # Returns:
  #
  # *   `self.real <=> object.real` if both of the following are true:
  #
  #     *   `self.imag == 0`.
  #     *   `object.imag == 0`. # Always true if object is numeric but not
  #         complex.
  #
  #
  # *   `nil` otherwise.
  #
  #
  # Examples:
  #
  #     Complex(2) <=> 3             # => -1
  #     Complex(2) <=> 2             # => 0
  #     Complex(2) <=> 1             # => 1
  #     Complex(2, 1) <=> 1          # => nil # self.imag not zero.
  #     Complex(1) <=> Complex(1, 1) # => nil # object.imag not zero.
  #     Complex(1) <=> 'Foo'         # => nil # object.imag not defined.
  #
  def <=>: (untyped) -> Integer?

  # <!--
  #   rdoc-file=complex.c
  #   - complex == object -> true or false
  # -->
  # Returns `true` if `self.real == object.real` and `self.imag == object.imag`:
  #
  #     Complex(2, 3)  == Complex(2.0, 3.0)      # => true
  #
  def ==: (untyped) -> bool

  def >: (Numeric) -> bot

  def >=: (Numeric) -> bot

  # <!--
  #   rdoc-file=complex.c
  #   - abs -> float
  # -->
  # Returns the absolute value (magnitude) for `self`; see [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates):
  #
  #     Complex.polar(-1, 0).abs # => 1.0
  #
  # If `self` was created with [rectangular
  # coordinates](rdoc-ref:Complex@Rectangular+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.rectangular(1, 1).abs # => 1.4142135623730951 # The square root of 2.
  #
  def abs: () -> Numeric

  # <!--
  #   rdoc-file=complex.c
  #   - abs2 -> float
  # -->
  # Returns square of the absolute value (magnitude) for `self`; see [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates):
  #
  #     Complex.polar(2, 2).abs2 # => 4.0
  #
  # If `self` was created with [rectangular
  # coordinates](rdoc-ref:Complex@Rectangular+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.rectangular(1.0/3, 1.0/3).abs2 # => 0.2222222222222222
  #
  def abs2: () -> Numeric

  # <!-- rdoc-file=complex.c -->
  # Returns the argument (angle) for `self` in radians; see [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates):
  #
  #     Complex.polar(3, Math::PI/2).arg  # => 1.57079632679489660
  #
  # If `self` was created with [rectangular
  # coordinates](rdoc-ref:Complex@Rectangular+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.polar(1, 1.0/3).arg # => 0.33333333333333326
  #
  def angle: () -> Float

  # <!--
  #   rdoc-file=complex.c
  #   - arg -> float
  # -->
  # Returns the argument (angle) for `self` in radians; see [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates):
  #
  #     Complex.polar(3, Math::PI/2).arg  # => 1.57079632679489660
  #
  # If `self` was created with [rectangular
  # coordinates](rdoc-ref:Complex@Rectangular+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.polar(1, 1.0/3).arg # => 0.33333333333333326
  #
  alias arg angle

  def ceil: (*untyped) -> bot

  def coerce: (Numeric) -> [ Complex, Complex ]

  # <!-- rdoc-file=complex.c -->
  # Returns the conjugate of `self`, `Complex.rect(self.imag, self.real)`:
  #
  #     Complex.rect(1, 2).conj # => (1-2i)
  #
  def conj: () -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - conj -> complex
  # -->
  # Returns the conjugate of `self`, `Complex.rect(self.imag, self.real)`:
  #
  #     Complex.rect(1, 2).conj # => (1-2i)
  #
  def conjugate: () -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - denominator -> integer
  # -->
  # Returns the denominator of `self`, which is the [least common
  # multiple](https://en.wikipedia.org/wiki/Least_common_multiple) of
  # `self.real.denominator` and `self.imag.denominator`:
  #
  #     Complex.rect(Rational(1, 2), Rational(2, 3)).denominator # => 6
  #
  # Note that `n.denominator` of a non-rational numeric is `1`.
  #
  # Related: Complex#numerator.
  #
  def denominator: () -> Integer

  def div: (Numeric) -> bot

  def divmod: (Numeric) -> bot

  def dup: () -> self

  def eql?: (untyped) -> bool

  # <!--
  #   rdoc-file=complex.c
  #   - fdiv(numeric) -> new_complex
  # -->
  # Returns `Complex(self.real/numeric, self.imag/numeric)`:
  #
  #     Complex(11, 22).fdiv(3) # => (3.6666666666666665+7.333333333333333i)
  #
  def fdiv: (Numeric) -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - finite? -> true or false
  # -->
  # Returns `true` if both `self.real.finite?` and `self.imag.finite?` are true,
  # `false` otherwise:
  #
  #     Complex(1, 1).finite?               # => true
  #     Complex(Float::INFINITY, 0).finite? # => false
  #
  # Related: Numeric#finite?, Float#finite?.
  #
  def finite?: () -> bool

  def floor: (?Integer) -> bot

  # <!--
  #   rdoc-file=complex.c
  #   - hash -> integer
  # -->
  # Returns the integer hash value for `self`.
  #
  # Two Complex objects created from the same values will have the same hash value
  # (and will compare using #eql?):
  #
  #     Complex(1, 2).hash == Complex(1, 2).hash # => true
  #
  def hash: () -> Integer

  def i: () -> bot

  # <!-- rdoc-file=complex.c -->
  # Returns the imaginary value for `self`:
  #
  #     Complex(7).imaginary      #=> 0
  #     Complex(9, -4).imaginary  #=> -4
  #
  # If `self` was created with [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.polar(1, Math::PI/4).imag # => 0.7071067811865476 # Square root of 2.
  #
  def imag: () -> Numeric

  # <!--
  #   rdoc-file=complex.c
  #   - imag -> numeric
  # -->
  # Returns the imaginary value for `self`:
  #
  #     Complex(7).imaginary      #=> 0
  #     Complex(9, -4).imaginary  #=> -4
  #
  # If `self` was created with [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.polar(1, Math::PI/4).imag # => 0.7071067811865476 # Square root of 2.
  #
  def imaginary: () -> Numeric

  # <!--
  #   rdoc-file=complex.c
  #   - infinite? -> 1 or nil
  # -->
  # Returns `1` if either `self.real.infinite?` or `self.imag.infinite?` is true,
  # `nil` otherwise:
  #
  #     Complex(Float::INFINITY, 0).infinite? # => 1
  #     Complex(1, 1).infinite?               # => nil
  #
  # Related: Numeric#infinite?, Float#infinite?.
  #
  def infinite?: () -> Integer?

  # <!--
  #   rdoc-file=complex.c
  #   - inspect -> string
  # -->
  # Returns a string representation of `self`:
  #
  #     Complex(2).inspect                      # => "(2+0i)"
  #     Complex('-8/6').inspect                 # => "((-4/3)+0i)"
  #     Complex('1/2i').inspect                 # => "(0+(1/2)*i)"
  #     Complex(0, Float::INFINITY).inspect     # => "(0+Infinity*i)"
  #     Complex(Float::NAN, Float::NAN).inspect # => "(NaN+NaN*i)"
  #
  def inspect: () -> String

  def integer?: () -> bool

  # <!-- rdoc-file=complex.c -->
  # Returns the absolute value (magnitude) for `self`; see [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates):
  #
  #     Complex.polar(-1, 0).abs # => 1.0
  #
  # If `self` was created with [rectangular
  # coordinates](rdoc-ref:Complex@Rectangular+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.rectangular(1, 1).abs # => 1.4142135623730951 # The square root of 2.
  #
  alias magnitude abs

  def modulo: (Numeric) -> bot

  def negative?: () -> bot

  def nonzero?: () -> self?

  # <!--
  #   rdoc-file=complex.c
  #   - numerator -> new_complex
  # -->
  # Returns the Complex object created from the numerators of the real and
  # imaginary parts of `self`, after converting each part to the [lowest common
  # denominator](https://en.wikipedia.org/wiki/Lowest_common_denominator) of the
  # two:
  #
  #     c = Complex(Rational(2, 3), Rational(3, 4)) # => ((2/3)+(3/4)*i)
  #     c.numerator                                 # => (8+9i)
  #
  # In this example, the lowest common denominator of the two parts is 12; the two
  # converted parts may be thought of as Rational(8, 12) and Rational(9, 12),
  # whose numerators, respectively, are 8 and 9; so the returned value of
  # `c.numerator` is `Complex(8, 9)`.
  #
  # Related: Complex#denominator.
  #
  def numerator: () -> Complex

  # <!-- rdoc-file=complex.c -->
  # Returns the argument (angle) for `self` in radians; see [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates):
  #
  #     Complex.polar(3, Math::PI/2).arg  # => 1.57079632679489660
  #
  # If `self` was created with [rectangular
  # coordinates](rdoc-ref:Complex@Rectangular+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.polar(1, 1.0/3).arg # => 0.33333333333333326
  #
  alias phase angle

  # <!--
  #   rdoc-file=complex.c
  #   - polar -> array
  # -->
  # Returns the array `[self.abs, self.arg]`:
  #
  #     Complex.polar(1, 2).polar # => [1.0, 2.0]
  #
  # See [Polar Coordinates](rdoc-ref:Complex@Polar+Coordinates).
  #
  # If `self` was created with [rectangular
  # coordinates](rdoc-ref:Complex@Rectangular+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.rect(1, 1).polar # => [1.4142135623730951, 0.7853981633974483]
  #
  def polar: () -> [ Numeric, Float ]

  def positive?: () -> bot

  # <!--
  #   rdoc-file=complex.c
  #   - complex / numeric -> new_complex
  # -->
  # Returns the quotient of `self` and `numeric`:
  #
  #     Complex(2, 3)  / Complex(2, 3)  # => ((1/1)+(0/1)*i)
  #     Complex(900)   / Complex(1)     # => ((900/1)+(0/1)*i)
  #     Complex(-2, 9) / Complex(-9, 2) # => ((36/85)-(77/85)*i)
  #     Complex(9, 8)  / 4              # => ((9/4)+(2/1)*i)
  #     Complex(20, 9) / 9.8            # => (2.0408163265306123+0.9183673469387754i)
  #
  def quo: (Numeric) -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - rationalize(epsilon = nil) -> rational
  # -->
  # Returns a Rational object whose value is exactly or approximately equivalent
  # to that of `self.real`.
  #
  # With no argument `epsilon` given, returns a Rational object whose value is
  # exactly equal to that of `self.real.rationalize`:
  #
  #     Complex(1, 0).rationalize              # => (1/1)
  #     Complex(1, Rational(0, 1)).rationalize # => (1/1)
  #     Complex(3.14159, 0).rationalize        # => (314159/100000)
  #
  # With argument `epsilon` given, returns a Rational object whose value is
  # exactly or approximately equal to that of `self.real` to the given precision:
  #
  #     Complex(3.14159, 0).rationalize(0.1)          # => (16/5)
  #     Complex(3.14159, 0).rationalize(0.01)         # => (22/7)
  #     Complex(3.14159, 0).rationalize(0.001)        # => (201/64)
  #     Complex(3.14159, 0).rationalize(0.0001)       # => (333/106)
  #     Complex(3.14159, 0).rationalize(0.00001)      # => (355/113)
  #     Complex(3.14159, 0).rationalize(0.000001)     # => (7433/2366)
  #     Complex(3.14159, 0).rationalize(0.0000001)    # => (9208/2931)
  #     Complex(3.14159, 0).rationalize(0.00000001)   # => (47460/15107)
  #     Complex(3.14159, 0).rationalize(0.000000001)  # => (76149/24239)
  #     Complex(3.14159, 0).rationalize(0.0000000001) # => (314159/100000)
  #     Complex(3.14159, 0).rationalize(0.0)          # => (3537115888337719/1125899906842624)
  #
  # Related: Complex#to_r.
  #
  def rationalize: (?Numeric eps) -> Rational

  # <!--
  #   rdoc-file=complex.c
  #   - real -> numeric
  # -->
  # Returns the real value for `self`:
  #
  #     Complex(7).real      #=> 7
  #     Complex(9, -4).real  #=> 9
  #
  # If `self` was created with [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.polar(1, Math::PI/4).real # => 0.7071067811865476 # Square root of 2.
  #
  def real: () -> Numeric

  # <!--
  #   rdoc-file=complex.c
  #   - real? -> false
  # -->
  # Returns `false`; for compatibility with Numeric#real?.
  #
  def real?: () -> false

  # <!-- rdoc-file=complex.c -->
  # Returns a new Complex object formed from the arguments, each of which must be
  # an instance of Numeric, or an instance of one of its subclasses: Complex,
  # Float, Integer, Rational; see [Rectangular
  # Coordinates](rdoc-ref:Complex@Rectangular+Coordinates):
  #
  #     Complex.rect(3)             # => (3+0i)
  #     Complex.rect(3, Math::PI)   # => (3+3.141592653589793i)
  #     Complex.rect(-3, -Math::PI) # => (-3-3.141592653589793i)
  #
  # Complex.rectangular is an alias for Complex.rect.
  #
  def rect: () -> [ Numeric, Numeric ]

  # <!--
  #   rdoc-file=complex.c
  #   - rect -> array
  # -->
  # Returns the array `[self.real, self.imag]`:
  #
  #     Complex.rect(1, 2).rect # => [1, 2]
  #
  # See [Rectangular Coordinates](rdoc-ref:Complex@Rectangular+Coordinates).
  #
  # If `self` was created with [polar
  # coordinates](rdoc-ref:Complex@Polar+Coordinates), the returned value is
  # computed, and may be inexact:
  #
  #     Complex.polar(1.0, 1.0).rect # => [0.5403023058681398, 0.8414709848078965]
  #
  # Complex#rectangular is an alias for Complex#rect.
  #
  alias rectangular rect

  def reminder: (Numeric) -> bot

  def round: (*untyped) -> bot

  def step: (*untyped) ?{ (*untyped) -> untyped } -> bot

  # <!--
  #   rdoc-file=complex.c
  #   - to_c -> self
  # -->
  # Returns `self`.
  #
  def to_c: () -> Complex

  # <!--
  #   rdoc-file=complex.c
  #   - to_f -> float
  # -->
  # Returns the value of `self.real` as a Float, if possible:
  #
  #     Complex(1, 0).to_f              # => 1.0
  #     Complex(1, Rational(0, 1)).to_f # => 1.0
  #
  # Raises RangeError if `self.imag` is not exactly zero (either `Integer(0)` or
  # `Rational(0, *n*)`).
  #
  def to_f: () -> Float

  # <!--
  #   rdoc-file=complex.c
  #   - to_i -> integer
  # -->
  # Returns the value of `self.real` as an Integer, if possible:
  #
  #     Complex(1, 0).to_i              # => 1
  #     Complex(1, Rational(0, 1)).to_i # => 1
  #
  # Raises RangeError if `self.imag` is not exactly zero (either `Integer(0)` or
  # `Rational(0, *n*)`).
  #
  def to_i: () -> Integer

  alias to_int to_i

  # <!--
  #   rdoc-file=complex.c
  #   - to_r -> rational
  # -->
  # Returns the value of `self.real` as a Rational, if possible:
  #
  #     Complex(1, 0).to_r              # => (1/1)
  #     Complex(1, Rational(0, 1)).to_r # => (1/1)
  #
  # Raises RangeError if `self.imag` is not exactly zero (either `Integer(0)` or
  # `Rational(0, *n*)`).
  #
  # Related: Complex#rationalize.
  #
  def to_r: () -> Rational

  # <!--
  #   rdoc-file=complex.c
  #   - to_s -> string
  # -->
  # Returns a string representation of `self`:
  #
  #     Complex(2).to_s                      # => "2+0i"
  #     Complex('-8/6').to_s                 # => "-4/3+0i"
  #     Complex('1/2i').to_s                 # => "0+1/2i"
  #     Complex(0, Float::INFINITY).to_s     # => "0+Infinity*i"
  #     Complex(Float::NAN, Float::NAN).to_s # => "NaN+NaN*i"
  #
  def to_s: () -> String

  def truncate: (?Integer) -> bot

  def zero?: () -> bool
end

# <!-- rdoc-file=complex.c -->
# Equivalent to `Complex(0, 1)`:
#
#     Complex::I # => (0+1i)
#
Complex::I: Complex