Six PDFs calculated for Procyon from different modes of SAPP: (a) asteroseismology, (b) spectroscopy, (c) photometry and parallax, (d) spectroscopy and asteroseismology (this is analogue to our constrained spectroscopy + ν_max prior results described in Sect. 4.1), (e) spectroscopy and photometry (with parallax), and (f) combined (Bayesian scheme). The horizontal axis is effective temperature, the vertical axes is surface gravity, and the colour bar is the logarithm of probability. Each PDF is sliced in the [Fe/H] dimension. The grey solid line represents a stellar evolution track with 1.5 M_⊙ and Z = Z_⊙ (the pre-main sequence is not included). The white cross represents the best-fit value for the given PDF.