[petsc-dev] vector inner products

[Munson, Todd]

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.