We present an analytical treatment of the Camley-Barnas theory of the giant
magnetoresistance (GMR) in magnetic layered structures and obtain an exact
and general expression for the resistivity. We used this expression to eva
luate the resistivity and GMR numerically, comparing the results with exper
imental observations. (C) 2000 American Institute of Physics. [S0021-8979(0
0)08619-9].