Nicolas Tancogne-Dejean requested to merge preconditioned_linear_solver_cg into develop Jan 21, 2021

Description

The CG linear solver now uses the preconditioner, for faster convergence.

News snippet

The CG linear solver now uses the preconditioner, for faster convergence.

Checklist

I have checked that my code follows the Octopus coding standards
I have added tests for all the new features added in this request.