Numerical Evaluation of the Fermi Beta-Distribution Function

In making a Fermi-Kurie plot of a $\beta$-spectrum various approximations have been used to evaluate $f(Z,\eta )$. It is probable, however, that none of these approximations is completely adequate for all values of $Z$ and $\eta$. Hence an accurate computation and tabulation of this important function is now in preparation. Three approximations for $f(Z,\eta )$ are compared with some representative values of $f(Z,\eta )$ that have been computed for the proposed table, and the accuracy and range of validity of these approximations are indicated.