jose-antonio-torres
**Current status**: After PR, we will have linear filters solved with a direct solver, and nonlinear filters solved with a gradient method. The goal is to merge both kind of filters, allowing gradient method for any filter (even linear), while keeping the possibility to solve the linear filters with a direct solver. **Main classes/functions**: **Outline of the solution** - [ ] Step 1 - [ ] ... ---- *Assigned to:* *Wingman:*