Root-mean-square of nonlinear fluctuations of cosmic matter field as function of the smoothing mass M. The linear fluctuations σ_L (computed with MGCAMB) are represented by dashed lines, while the solid curves correspond to the σ_NL, the nonlinear fluctuations of cosmic matter field (computed from the z = 0 snapshots of the DUSTGRAIN-pathfinder simulations). The internal panel contains the corresponding linear and nonlinear power spectra.