Jacobi preconditioner

In the work of Lindborg et al [119], the resulting linear equation systems were solved with preconditioned Krylov subspace projection methods [166]. The Poisson equation was solved by a conjugate gradient (CG)-solver, while the other transport equations were solved using a bi-conjugate gradient (BCG)-solver which can handle also non-symmetric equations systems. The solvers were preconditioned with a Jacobi preconditioner. 

Both preconditioners are normally very robust and efficient, but the ILU-preconditioner can introduce small numerical perturbations due to floating point round-off error. Thus, simulations of symmetric problems may give non-symmetric results after some time. For this reason the Jacobi preconditioner is recommended. 

Solver with the Fourier-Jacobi Preconditioner for the Anisotropic EIT/EEG Forward Problem. Comp. Math. Methods in Medicine 1-12. 

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