Inversion

Instead of approximating the Hessian with a diagonal matrix we can attempt to estimate the least squares inverse using a conjugate gradient solver. The model is preconditioned by using polynomial division to apply the helical derivative and the new preconditioned variable $\bf p$ is estimated through  

$$Q(\bf p) = \vert\vert\bf d- \bf L \bf C \bf p\vert\vert^2 + \epsilon^2 \vert\vert \bf p\vert\vert^2 ,$$ (11)

where $\bf m= \bf C \bf p$.
 

• Implementation
• Results