(self)
return self.wavelength*self._frequency
Returns the speed of travelling wave.
        It is medium dependent.

        Examples
        ========

        >>> from sympy import symbols
        >>> from sympy.physics.optics import TWave
        >>> A, phi, f = symbols('A, phi, f')
        >>> w = TWave(A, f, phi)
        >>> w.speed
        c/n
Returns the speed of travelling wave.
        It is medium dependent.
Returns the speed of travelling wave . It is medium dependent .
def speed(self):
        """
        Returns the speed of travelling wave.
        It is medium dependent.

        Examples
        ========

        >>> from sympy import symbols
        >>> from sympy.physics.optics import TWave
        >>> A, phi, f = symbols('A, phi, f')
        >>> w = TWave(A, f, phi)
        >>> w.speed
        c/n
        """
        return self.wavelength*self._frequency
def speed ( self ) : return self . wavelength * self . _frequency