Interpolation of dy

[totork]

I try to understand the interpolated values for dy for the grids. For some W7-X grids, the dys and the corresponding interpolations are

Here, for y=0, the backward interpolated value is deviating from the others, which should not be be case from my understanding. Equally for y=-1, the forward interpolated values are

[bshanahan]

Is this not because the grid is wrapping around? So at y=0, the backward y should hit the last plane, and at y=-1, the forward y should hit the first one.

[dschwoerer]

This should be fixed in master?