def R0(h, k, L, A):
    """ Resistance between ambient and first node // applies to end node as well

	Parameters
	----------	
	h : float or (m,) np.array
		covection resistance [W/(m2K)]

	k : float or (m,) np.array
		material thermal conductivity [W/(mK)]

	L : float or (m,) np.array
		thickness of the sample [m]
		
	A : float or (m,) np.array
		sample area perpendicular to the direction of heat transfer [m2]

	Returns
	-------
	R : float or (m,) np.array
		heat transfer resistance [K/W]
	
	Example use
	-----------
	>>> XXX		 
	"""
    return L / (2 * k * A) + 1 / (h * A)
