# tree_d_3d.kernels.fmm_evaluate.fmm_evaluate_pyccel

*module*

The Pyccel version (CPU) of the ``fmm_evaluate`` kernel of the Barnes-Hut and FMM solvers.

``fmm_evaluate_cuda.cu`` next to this file is the CUDA version (GPU) and ``fmm_evaluate_numpy.py`` the
version for machines without Pyccel, all with the same arguments; the folder's
``__init__.py`` declares the kernel (see :mod:`tree_d_3d.kernels`). The flat
quadtree is described in :mod:`tree_d_3d.flat_tree`.

[View source](https://github.com/max-models/tree-d-3d/blob/devel/src/tree_d_3d/kernels/fmm_evaluate/fmm_evaluate_pyccel.py#L1-L1)

## tree_d_3d.kernels.fmm_evaluate.fmm_evaluate_pyccel.fmm_evaluate

*function*

```python
def fmm_evaluate(pos: float[:, :], charge: float[:], perm: int64[:], node_count: int, node_center: float[:, :], node_start: int64[:], node_end: int64[:], node_child: int64[:], local_re: float[:, :], local_im: float[:, :], pairs: int64[:, :], count: int, softening: float, with_potential: int, phi: float[:], field: float[:, :], status: int64[:]) -> None
```

Far field from leaf local expansions plus exact mutual near field.

Every particle is a target; self-interaction is excluded. With
``with_potential = 0`` the near-field potential is skipped, which saves
a logarithm per pair when only forces are needed. ``status[0]`` becomes
1 + a particle that met an unsoftened coincident charge.

[View source](https://github.com/max-models/tree-d-3d/blob/devel/src/tree_d_3d/kernels/fmm_evaluate/fmm_evaluate_pyccel.py#L15-L95)