I also tried to divide the norm by m*n , which is the number of grids, the trend of norm still increases.
Thanks! Weizhuo Matthew Knepley <knep...@gmail.com> 于2018年10月1日周一 下午7:45写道: > On Mon, Oct 1, 2018 at 6:31 PM Weizhuo Wang <weizh...@illinois.edu> wrote: > >> Hi! >> >> I'm recently trying out the example code provided with the KSP solver >> (ex12.c). I noticed that the mean norm of the grid increases as I use finer >> meshes. For example, the mean norm is 5.72e-8 at m=10 n=10. However at >> m=100, n=100, mean norm increases to 9.55e-6. This seems counter intuitive, >> since most of the time error should decreases when using finer grid. Am I >> doing this wrong? >> > > The norm is misleading in that it is the l_2 norm, meaning just the sqrt > of the sum of the squares of > the vector entries. It should be scaled by the volume element to > approximate a scale-independent > norm (like the L_2 norm). > > Thanks, > > Matt > > >> Thanks! >> -- >> Wang Weizhuo >> > > > -- > What most experimenters take for granted before they begin their > experiments is infinitely more interesting than any results to which their > experiments lead. > -- Norbert Wiener > > https://www.cse.buffalo.edu/~knepley/ > <http://www.cse.buffalo.edu/~knepley/> > -- Wang Weizhuo