`x` vs `y` in documentation
DenseVector::axpy(a, y) method is documented as
vector space axpy operation ( *this += a y )
The same for
y := ax + y which matches
axpy = alpha x plus y. The parameter naming in DUNE doesn't match this and is therefore confusing.
In other places DUNE uses
y as the result: for example
FieldMatrix::mv(x, y) computes
y := Ax.
I propose to rename the parameters so that
y always is the name of the result.