@lindahua Thanks. I forgot the BLAS allows that. 

I'll add some tests for the `norm`s. Actually there are no specific tests for norm at all. Much testing is still needed for `SubArrays` in the BLAS and LAPACK code as the `stride` is not always calculated correct. I guess it hasn't been a problem because `sub` has been so slow, but this will probably change when people start to use fast views.