Auxiliary
boundaries(boxsize, level, level_zoom, NPART_zoom, offset_from_code, cut_from_sides, gridscale)
:math:\vspace{-1mm}
Calculate bounding boxes, fine grid offsets and other quantities useful when dealing with a MUSIC snapshot.
Arguments:
-
The first three arguments must be set to the following parameters from the MUSIC configuration file::
[boundaries() argument] [parameter from MUSIC .conf] [type] boxsize = boxlength float level = levelmin int level_zoom = levelmax int
With the included MUSIC configuration file, :download:ics.conf
<./ics.conf>, the above three arguments take the values:
100.0, 9, 10.
-
NPART_zoom-- list of three integers, giving the size of the fine grid. -
offset_from_code-- list of three integers, giving the crude-grid index coordinates of the origin of the fine grid. -
The last two parameters define the COLA volume and the size of the PM grid:
-
cut_from_sides-- a list of two integers, call them :math:a,b. Then, the Lagrangian COLA volume in terms of the indices of the particle displacements arrays,s:sub:i, at levellevel(the one covering the full box) is given by the following array slice::si[a:2level-b,a:2level-b,a:2**level-b]
-
gridscale-- an integer. Sets the size of the PM grid in each dimension togridscaletimes the particle number at levellevelin that dimension within the COLA volume.
-
Return:
-
BBox_in,offset_zoom,cellsize,cellsize_zoom-- the same as in :func:ic.ic_2lptbut the first two give the bounding box and offset of the refinement region with respect to the COLA volume. -
offset_index-- a 3-vector of integers. The same asoffset_zoombut in units of the crude-particle index. -
BBox_out-- a 3x2 array of integers. Gives the bounding box at levellevelthat resides in the COLA volume. It equals[[a,2**level-b],[a,2**level-b],[a,2**level-b]](see the description of the argumentcut_from_sidesabove). -
BBox_out_zoom-- the same asBBox_outbut for the fine particles (as levellevel_zoom) included in the COLA volume. -
ngrid_x, ngrid_y, ngrid_z-- integers. The size of the PM grid used in the COLA volume. -
gridcellsize-- a float. The PM grid spacing in :math:\mathrm{Mpc}/h.
Example: For example usage, see the worked out example in (todo).
Source code in pycola3/aux.py
def boundaries(
boxsize, level, level_zoom, NPART_zoom, offset_from_code, cut_from_sides, gridscale
):
"""
:math:`\\vspace{-1mm}`
Calculate bounding boxes, fine grid offsets and other
quantities useful when dealing with a MUSIC snapshot.
**Arguments**:
* The first three arguments must be set to the following parameters
from the MUSIC configuration file::
[boundaries() argument] [parameter from MUSIC .conf] [type]
boxsize = boxlength float
level = levelmin int
level_zoom = levelmax int
With the included MUSIC configuration file, :download:`ics.conf
<./ics.conf>`, the above three arguments take the values:
100.0, 9, 10.
* ``NPART_zoom`` -- list of three integers, giving the size of the
fine grid.
* ``offset_from_code`` -- list of three integers, giving the
crude-grid index coordinates of the origin of the fine grid.
* The last two parameters define the COLA volume and the size of the PM grid:
- ``cut_from_sides`` -- a list of two integers, call them :math:`a,b`.
Then, the Lagrangian COLA volume in terms of the indices of
the particle displacements arrays, ``s``:sub:`i`, at level ``level``
(the one covering the full box) is given by the following
array slice::
si[a:2**level-b,a:2**level-b,a:2**level-b]
- ``gridscale`` -- an integer. Sets the size of the PM grid in
each dimension to ``gridscale`` times the particle number at
level ``level`` in that dimension within the COLA volume.
**Return**:
* ``BBox_in,offset_zoom,cellsize,cellsize_zoom`` -- the same as in
:func:`ic.ic_2lpt` but the first two give the bounding box and
offset of the refinement region with respect to the COLA volume.
* ``offset_index`` -- a 3-vector of integers. The same as
``offset_zoom`` but in units of the crude-particle index.
* ``BBox_out`` -- a 3x2 array of integers. Gives the bounding box
at level ``level`` that resides in the COLA volume. It equals
``[[a,2**level-b],[a,2**level-b],[a,2**level-b]]`` (see the
description of the argument ``cut_from_sides`` above).
* ``BBox_out_zoom`` -- the same as ``BBox_out`` but for the fine
particles (as level ``level_zoom``) included in the COLA volume.
* ``ngrid_x, ngrid_y, ngrid_z`` -- integers. The size of the PM
grid used in the COLA volume.
* ``gridcellsize`` -- a float. The PM grid spacing in
:math:`\mathrm{Mpc}/h`.
**Example**: For example usage, see the worked out example in (todo).
"""
NPART = (2 ** level, 2 ** level, 2 ** level)
cellsize = boxsize / 2.0 ** level
cellsize_zoom = boxsize / 2.0 ** level_zoom
gridcellsize = (cellsize) / float(gridscale)
BBox_out = np.array(
[
[cut_from_sides[0], NPART[0] - cut_from_sides[1]],
[cut_from_sides[0], NPART[1] - cut_from_sides[1]],
[cut_from_sides[0], NPART[2] - cut_from_sides[1]],
],
dtype="int32",
)
ind0 = [0, 0, 0]
ind1 = list(NPART_zoom[:])
for i in range(3):
if cut_from_sides[0] > offset_from_code[i]:
ind0[i] = (cut_from_sides[0] - offset_from_code[i]) * 2 ** (
level_zoom - level
)
if (NPART[i] - cut_from_sides[1] - offset_from_code[i]) * 2 ** (
level_zoom - level
) < NPART_zoom[i]:
ind1[i] = (NPART[i] - cut_from_sides[1] - offset_from_code[i]) * 2 ** (
level_zoom - level
)
BBox_out_zoom = np.array(
[[ind0[0], ind1[0]], [ind0[1], ind1[1]], [ind0[2], ind1[2]]], dtype="int32"
)
# offset index of small sim box relative to large sim box (NOTE: sim, not IC boxes!!!)
offset_index = (
np.array(offset_from_code, dtype="int32")
+ BBox_out_zoom[:, 0] // 2 ** (level_zoom - level)
- BBox_out[:, 0]
)
offset_zoom = (
offset_index * cellsize
- np.array([cellsize_zoom, cellsize_zoom, cellsize_zoom], dtype="float32") / 2.0
)
# bbox of small sim box relative to large sim box in large sim coo
BBox_in = np.array(
[
[
offset_index[0],
offset_index[0]
+ (BBox_out_zoom[0, 1] - BBox_out_zoom[0, 0])
// 2 ** (level_zoom - level),
],
[
offset_index[1],
offset_index[1]
+ (BBox_out_zoom[1, 1] - BBox_out_zoom[1, 0])
// 2 ** (level_zoom - level),
],
[
offset_index[2],
offset_index[2]
+ (BBox_out_zoom[2, 1] - BBox_out_zoom[2, 0])
// 2 ** (level_zoom - level),
],
],
dtype="int32",
)
ngrid_x = (BBox_out[0, 1] - BBox_out[0, 0]) * gridscale
ngrid_y = (BBox_out[1, 1] - BBox_out[1, 0]) * gridscale
ngrid_z = (BBox_out[2, 1] - BBox_out[2, 0]) * gridscale
return (
BBox_in,
offset_zoom,
cellsize,
cellsize_zoom,
offset_index,
BBox_out,
BBox_out_zoom,
ngrid_x,
ngrid_y,
ngrid_z,
gridcellsize,
)