NumCosmoGrowthFunceval_deriv

This function evaluates the derivative of the normalized growth function $\mathrm{d}D/\mathrm{d}a$ at redshift $z$, also called as linear growth rate. Where $a$ is the scale factor.

Note that this definition is different from the one normally applied in redshift-space distortion studies. These studies use the parameter given by, \begin{equation} f(z) = \left. \frac{\mathrm{d}\ln D}{\mathrm{d} \ln a} \right|{z} = -\frac{(1 + z)}{D(z)} \left. \frac{\mathrm{d} D}{\mathrm{d} a} \right|{z} \,\, . \end{equation} For more details see e.g. [Zarrouk et al. (2018)][X2018MNRAS.477.1639Z] [arXiv].