-
Notifications
You must be signed in to change notification settings - Fork 19
/
common.py
46 lines (44 loc) · 1.79 KB
/
common.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
#!/usr/bin/env python3
## vi: tabstop=4 shiftwidth=4 softtabstop=4 expandtab
## ---------------------------------------------------------------------
##
## Copyright (C) 2020 by the adcc authors
##
## This file is part of adcc.
##
## adcc is free software: you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published
## by the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## adcc is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with adcc. If not, see <http://www.gnu.org/licenses/>.
##
## ---------------------------------------------------------------------
import numpy as np
def select_eigenpairs(eigenvalues, n_ep, which):
"""
Return a numpy `bool` mask selecting the `n_ep` eigenpairs of the `which`
criterion. It is assumed that the `eigenvalues` are sorted algebraically
from the smallest to the largest.
"""
mask = np.zeros(len(eigenvalues), dtype=bool)
if which == "LA": # Largest algebraic
mask[-n_ep:] = True
elif which == "SA": # Smallest algebraic
mask[:n_ep] = True
elif which == "LM": # Largest magnitude
sorti = np.argsort(np.abs(eigenvalues))[-n_ep:]
mask[sorti] = True
elif which == "SM": # Smallest magnitude
sorti = np.argsort(np.abs(eigenvalues))[:n_ep]
mask[sorti] = True
else:
raise ValueError("For now only the values 'LM', 'LA', 'SM' and 'SA' "
"are understood for 'which'.")
return mask.nonzero()[0]