Abstract
Formulas for the direct calculation of convolved photoabsorption cross sections are presented. Atomic parameters used for the calculation of infinite resolution cross sections can be used in a very accurate approximate formula for the convolved cross section. The direct calculation of convolved cross sections is usually 20–100 times faster than the calculation of numerically convolved cross sections. Numerically convolved cross sections are compared to the preconvolved cross section for a recent atomic calculation.