Inverse Jacobi multiplier

Given a vector field ZX(M) on a n-dimensional manifold M with a distinguished volume form Ω, an inverse Jacobi multiplier (or inverse multiplier) is a smooth function Δ such that

kZkΔxk=Δdiv(Z)

or

Z(Δ)Δ=div(Z)

See @berrone2003inverse page 14. But also, this is the definition given in @hu2015inverse for inverse integrating factor.

It is satisfied that if Δ is an inverse Jacobi multiplier then 1/Δ is a Jacobi last multiplier.

It can be shown that the product of symmetrising factors is an inverse Jacobi multiplier. See the paper "symfactor", or the video 003 and xournal 199.