cos

# File lib/cmath.rb, line 170
  def cos(z)
    begin
      if z.real?
        cos!(z)
      else
        Complex(cos!(z.real) * cosh!(z.imag),
                -sin!(z.real) * sinh!(z.imag))
      end
    rescue NoMethodError
      handle_no_method_error
    end
  end