heleeprocessor

Hi all,

I am using the heLeeprocessor3D.hh,Now I ’ d like to change the collidingBubbles3d to 2Dimension.
but the heLeeprocessor3d,hh has the classes centralGradient ,biasedGradient and laplacian.
I want to know the literature about that class.
could you teach me the paper or everything ?

best regards.

motti