py3nj

A small python library to calcluate wigner's 3j-, 6j- and 9j- symbols. py3nj is designed to be compatible with numpy's np.ndarray and its calculation is vectorized automatically.

Basic Usage

The basic interfaces are py3nj.wigner3j, py3nj.wigner6j, py3nj.wigner9j, and py3nj.clebsch_gordan.

>>> # Calculate (0/2, 1/2, 1/2,
... #           (0/2, 1/2,-1/2)
... # Note that all the arguments should be doubled
... py3nj.wigner3j(0, 1, 1,
...                0, 1,-1)
0.7071067811865476

>>> # vectorization is supported
... py3nj.wigner3j([0, 2], [1, 0], [ 1, 0],
...                [0, 0], [1, 0], [-1, 0])
array([0.70710678, 0.        ])

>>> # 6J symbol
>>> py3nj.wigner6j([2, 1], [1, 2], [1, 1],
...                [1, 2], [2, 1], [0, 0])
array([0.40824829, 0.40824829])

>>> # 9J symbol
>>> py3nj.wigner9j([2, 2], [4, 4], [2, 2],
...                [2, 4], [2, 6], [2, 2],
...                [2, 2], [2, 4], [2, 2])
array([0.05555556, 0.03651484])

>>> Clebsch Gordanh coefficient
>>> py3nj.clebsch_gordan(2, 2, 4,
...                      2, 0, 2)
0.7071067811865475

>>> # Vectorized calcluation of C.G. coef
... py3nj.clebsch_gordan([2, 1], [2, 1], [4, 0],
...                      [2,-1], [0, 1], [2, 0])
array([ 0.70710678, -0.70710678])

Install

py3nj can be installed through either pip or github repository. You'll likely need to have ninja installed.

Install by pip

pip install py3nj

Install through github

git clone https://github.com/fujiisoup/py3nj
cd py3nj
pip install .

Acknowledgement

py3nj wraps slatec fortran implementation. See http://www.netlib.org/slatec/ for the details.

License

Copyright 2018, py3nj Developers

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.