Summary:
This diff added ProductAdditiveQuantizer.
A Simple Algo description:
1. Divide the vector space into several orthogonal sub-spaces, just like PQ does.
2. Quantize each sub-space by an independent additive quantizer.
Usage:
Construct a ProductAdditiveQuantizer object:
- `d`: dimensionality of the input vectors
- `nsplits`: number of sub-spaces divided into
- `Msub`: `M` of each additive quantizer
- `nbits`: `nbits` of each additive quantizer
```python
d = 128
nsplits = 2
Msub = 4
nbits = 8
plsq = faiss.ProductLocalSearchQuantizer(d, nsplits, Msub, nbits)
prq = faiss.ProductResidualQuantizer(d, nsplits, Msub, nbits)
```
Pull Request resolved: https://github.com/facebookresearch/faiss/pull/2286
Test Plan:
```
buck test //faiss/tests/:test_local_search_quantizer -- TestProductLocalSearchQuantizer
buck test //faiss/tests/:test_residual_quantizer -- TestProductResidualQuantizer
```
Reviewed By: alexanderguzhva
Differential Revision: D35907702
Pulled By: mdouze
fbshipit-source-id: 7428a196e6bd323569caa585c57281dd70e547b1
9b1982262a