Hello team, If I use KSPSolve for Ax=b using Matshell (a user-defined stencil equivalent of A) without preconditioning (since the standard PC would need information of the matrix so cannot apply it to matrix-free method), is it possible, or even inevitable to encounter significant slowdown compared to using a fully assembled matrix with a suitable preconditioner? I'm running a small example and it's already taking a long time for Matshell to converge.
Thanks for your help, Yuyun
