There is a bit of code in TAO that allows the user to change the norm to a matrix norm. This was introduced to get some mesh independent behavior in one example (tao/examples/tutorials/ex3.c). That norm, however, does not propagate down into the KSP methods and is only used for testing convergence of the nonlinear problem. A few questions then: Is similar functionality needed in SNES? Are TAO and SNES even the right place for this functionality? Should it belong to the Vector class so that you can change the inner products and have all the KSP methods (hopefully) work correctly? Note: that this discussion brings us to the brink of supporting an optimize-then-discretize approach. I am not convinced we should go down that rabbit hole. Thanks, Todd.