= Logarithmic linear growth rate
{title2=$f=d\ln D/d\ln a$}
For scale-independent linear growth $\delta(\mathbf k,a)=D(a)\delta_{\rm ini}(\mathbf k)$, the <logarithmic linear growth rate> measures fractional amplification per logarithmic change of the <scale factor>. In an <Einstein-de Sitter universe>, $D\propto a$ and $f=1$. The <cosmological Poisson equation> for conserved <pressureless matter> gives $\psi\propto D/a$ at fixed <comoving coordinate>, and therefore $\psi'=\mathcal H(f-1)\psi$. This relates suppression of matter growth to the <Integrated Sachs-Wolfe effect>.
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