The way to calculate a finite Hessian

[chobby]

Hi,

I'm very interested in the way how to get the finite Hessian.
And I found the formula in the source code as below

I would appreciate if you give me some information about the formula.

[Patrick Wieschollek]

Please have a look at finite differences. This is no magic here. The 2, 1 referring to eps added/subtracted to coordinates.