Add support for slicing / restricting the output domain.

[tehrengruber]

We would like to have something like this:

lap(in_field, offset_provider=offset_provider, backend="py", out=out_field[1:-1, 1:-1])

[lorenzovarese]

Currently, the laplacian operation exhibits the following behavior:

Executing 'test_lap' with args: py, constant_cartesian_domain, true
----------------------------------------------------------------------------
Input Matrix before applying the laplacian:
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
----------------------------------------------------------------------------
Output Matrix after applying lap() operator in the field operator:
-2.0  0.0   0.0   0.0   0.0   0.0   0.0   -1.0
-1.0  0.0   0.0   0.0   0.0   0.0   0.0   -1.0
-1.0  0.0   0.0   0.0   0.0   0.0   0.0   -1.0
-1.0  0.0   0.0   0.0   0.0   0.0   0.0   -1.0
-1.0  0.0   0.0   0.0   0.0   0.0   0.0   -1.0
-1.0  0.0   0.0   0.0   0.0   0.0   0.0   -1.0
-1.0  0.0   0.0   0.0   0.0   0.0   0.0   -1.0
-1.0  0.0   0.0   0.0   0.0   0.0   0.0   -2.0
----------------------------------------------------------------------------
Expected ground truth of laplacian computation without field operator:
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  0.0  0.0  0.0  0.0  0.0  0.0  1.0
1.0  0.0  0.0  0.0  0.0  0.0  0.0  1.0
1.0  0.0  0.0  0.0  0.0  0.0  0.0  1.0
1.0  0.0  0.0  0.0  0.0  0.0  0.0  1.0
1.0  0.0  0.0  0.0  0.0  0.0  0.0  1.0
1.0  0.0  0.0  0.0  0.0  0.0  0.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0


Executing 'test_lap' with args: py, simple_cartesian_domain, true
----------------------------------------------------------------------------
Input Matrix before applying the laplacian:
0.0   1.0   2.0   3.0   4.0 
5.0   6.0   7.0   8.0   9.0 
10.0  11.0  12.0  13.0  14.0
15.0  16.0  17.0  18.0  19.0
20.0  21.0  22.0  23.0  24.0
----------------------------------------------------------------------------
Output Matrix after applying lap() operator in the field operator:
6.0    24.0   24.0   24.0   19.0 
-4.0   0.0    0.0    0.0    -10.0
-9.0   0.0    0.0    0.0    -15.0
-14.0  0.0    0.0    0.0    -20.0
-43.0  -24.0  -24.0  -24.0  -54.0
----------------------------------------------------------------------------
Expected ground truth of laplacian computation without field operator:
0.0   1.0   2.0   3.0   4.0 
5.0   0.0   0.0   0.0   9.0 
10.0  0.0   0.0   0.0   14.0
15.0  0.0   0.0   0.0   19.0
20.0  21.0  22.0  23.0  24.0


Executing 'test_lap_lap' with args: py, constant_cartesian_domain, true
----------------------------------------------------------------------------
Input Matrix before applying the laplacian of laplacian (lap_lap):
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
----------------------------------------------------------------------------
Output Matrix after applying lap(lap()) operator in the field operator:
10.0  -3.0  0.0   0.0   0.0   0.0   -1.0  15.0
2.0   -1.0  0.0   0.0   0.0   0.0   -1.0  5.0 
3.0   -1.0  0.0   0.0   0.0   0.0   -1.0  6.0 
3.0   -1.0  0.0   0.0   0.0   0.0   -1.0  6.0 
3.0   -1.0  0.0   0.0   0.0   0.0   -1.0  6.0 
3.0   -1.0  0.0   0.0   0.0   0.0   -1.0  6.0 
3.0   -1.0  0.0   0.0   0.0   0.0   -1.0  5.0 
5.0   -1.0  0.0   0.0   0.0   0.0   -3.0  35.0
----------------------------------------------------------------------------
Expected ground truth of lap(lap()) computation without field operator:
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  0.0  0.0  0.0  0.0  1.0  1.0
1.0  1.0  0.0  0.0  0.0  0.0  1.0  1.0
1.0  1.0  0.0  0.0  0.0  0.0  1.0  1.0
1.0  1.0  0.0  0.0  0.0  0.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0
1.0  1.0  1.0  1.0  1.0  1.0  1.0  1.0


Executing 'test_lap_lap' with args: py, simple_cartesian_domain, true
----------------------------------------------------------------------------
Input Matrix before applying the laplacian of laplacian (lap_lap):
0.0   1.0   2.0   3.0   4.0 
5.0   6.0   7.0   8.0   9.0 
10.0  11.0  12.0  13.0  14.0
15.0  16.0  17.0  18.0  19.0
20.0  21.0  22.0  23.0  24.0
----------------------------------------------------------------------------
Output Matrix after applying lap(lap()) operator in the field operator:
16.0    -109.0  -72.0   -77.0   -58.0 
18.0    20.0    24.0    14.0    53.0  
28.0    -9.0    0.0     -15.0   60.0  
19.0    -38.0   -24.0   -44.0   48.0  
178.0   53.0    72.0    37.0    252.0 
----------------------------------------------------------------------------
Expected ground truth of lap(lap()) computation without field operator:
0.0   1.0   2.0   3.0   4.0 
5.0   6.0   7.0   8.0   9.0 
10.0  11.0  0.0   13.0  14.0
15.0  16.0  17.0  18.0  19.0
20.0  21.0  22.0  23.0  24.0

When developing this feature, it would be beneficial to test the behavior using the existing test suite and the debug print developed during the laplacian example. After implementing this feature, it would be valuable to add a test case that checks the border values after the laplacian computation.