Integral linear growth factor in a matter-Lambda universe
= Integral linear growth factor in a matter-Lambda universe
{title2=$D_+(a)$}
The growing solution of the matter perturbation equation in a spatially flat matter-plus-cosmological-constant universe is
$$
D_+(a)=\frac52\Omega_{m,0}H_0^2H(a)
\int_0^a\frac{da'}{a'^3H(a')^3},
$$
normalized so that $D_+(a)\sim a$ during early matter domination.