Representation of the magnetization characteristic by a sum of exponentials

It is possible to set up equations of the form
B(H) = a_{0} + a_{1} e^{-\alpha_{1}H} + a_{2} e^{-\alpha_{2}H} + a_{3} e^{-\alpha_{3}H} + a_{4} e^{-\alpha_{4}H}
on an analog computer to fit accurately a
B-H
curve of any magnetic material over the whole range from zero to the knee of the curve to the saturation part of the curve.