Line mass (source code)

= Line mass
{title2=$\lambda$}

The <line mass> is <mass> per unit <length> along a filament. For an axisymmetric <density profile> $\rho(R)$,
$$
\lambda=2\pi\int_0^\infty\rho(R)R\,dR,
$$
with the upper limit replaced by the filament radius when the density has compact support.