Wendland C6 missing neighbour contributions
w < 0 and/or dw_dx > 0 for at least some (maybe all) pairs with ~0.85 < x < 1 in kernel_deval with Wendland C6 and eta = 1.866. This might affect other kernels as well.
A reproducible test case on master branch:
- run hydro test examples/HydroTests/SodShock_3D as normal
- ./configure --with-hydro=minimal --with-kernel=wendland-C6 --disable-hand-vec
- set eta = 1.866 in .yml file
- To catch error: on line 277 of kernel_hydro.h (x < 0.85 is chosen to demonstrate the range of x affected without a fix, rather than to be an indicator of whether the problem is solved): if (x < 0.85 && w <= 0) error("Test Error: w = %.20f for x = %.20f", w, x);