1998A&A...337..699G

We present our numerical code to perform syntheses of galaxy spectra. Our modified linear simplex algorithm has the advantage that no initial solution is required, the non-negativity for the individual contributions is guaranteed, additional spectral components can be added and individual wavelength regions can be weighted. Synthesizing the observed galaxy spectra with isochrone spectra we determine the age distribution of the stellar component. We demonstrate the accuracy of our method to reconstruct the age distribution of theoretical spectra. Finally, we present evolutionary syntheses of the optical spectra of an elliptical galaxy and of the spatially resolved Seyfert galaxy NGC 1365.