Predicted light variations of HD 64740 computed taking into account the helium and silicon surface abundance distributions after Table 5 (solid lines: inhomogeneous iron distribution after Table 5, dashed lines: homogeneous iron distribution) compared with IUE and Hipparcos observations (dots). Upper panel: the far ultraviolet region. Observed and predicted fluxes were smoothed by a Gaussian filter as described in the text. Curves for individual wavelengths were vertically shifted. The region around C iv λ1548 and λ1551 lines was excluded from the analysis. Bottom panel: the optical region in the Hipparcos H_p filter.