Linear matter power spectrum (upper), the residuals Eq. (5) from the Eisenstein & Hu fit without baryons (middle), and the fractional residuals on P(k) compared to the truth for the Planck 2018 (Planck Collaboration VI 2020) cosmology. In all panels we plot the truth computed with CAMB with solid red lines, and the analytic fit Eq. (6) obtained in this paper with dashed blue lines. We see that the fit is accurate within 0.3% across all k considered.