cos

# File lib/cmath.rb, line 182
  def cos(z)
    begin
      if z.real?
        RealMath.cos(z)
      else
        Complex(RealMath.cos(z.real) * RealMath.cosh(z.imag),
                -RealMath.sin(z.real) * RealMath.sinh(z.imag))
      end
    rescue NoMethodError
      handle_no_method_error
    end
  end