I(r) = I_{0}e^{−r/R}

μ(r) = μ_{0} + \frac{r}{D}

I(r) = I_{0} e^{−K[( \frac{r}{R})^{1/4}−1]}

μ(r) = μ_{0} − K [(\frac{r}{R})^{1/4} − 1]