Analytic approximations for the incoherent X-ray intensities of the atoms from Ca to Am

Two analogue analytic functions containing three parameters and valid for the atoms Z ≥ 20 have been found, for accurately approximating both the well-known universal Bewilogua function and the atomic incoherent intensities computed by Cromer. The errors of the fits are not greater than the corresponding ones for the coherent intensities.