Performance improvement in creating Basis objects

.gitignore

@@ -14,7 +14,7 @@ __pycache__
 *.out
 
 # Project specific
-/Untitled.ipynb
+/examples
 /.ipynb_checkpoints/
 /build/
 /dist/

src/SumOfSquares/SoS.py

@@ -162,7 +162,7 @@ def poly_opt_prob(vars       : List[sp.Symbol],
                   deg        : Optional[int] = None,
                   sparse     : bool = False) -> SOSProblem:
     '''Formulates and returns a degree DEG Sum-of-Squares relaxation of a polynomial
-    optimization problem in variables VARS that mininizes OBJ subject to
+    optimization problem in variables VARS that minimizes OBJ subject to
     equality constraints EQS (g(x) = 0) and inequality constraints INEQS (h(x)
     >= 0). INEQ_PRODS determines if products of inequalities are used. SPARSE
     uses Newton polytope reduction to do computations in a reduced-size

src/SumOfSquares/basis.py

@@ -3,6 +3,7 @@
 import sympy as sp
 import numpy as np
 import math
+from functools import lru_cache
 from collections import defaultdict
 from typing import Iterable, Tuple, List, Union
 
@@ -39,19 +40,24 @@ def __init__(self, monoms: List[Tuple[int]]):
         self.nvars = len(monoms[0])
         self.is_hom = sum(sum(m) != self.deg for m in self.monoms) == 0
 
-        # A map from a monomial m (represented as tuple) to list of pairs (i, j)
-        # for all such pairs where m = basis[i]*basis[j].
-        self.sos_sym_entries = defaultdict(list)
-        for i, bi in enumerate(self):
-            for j, bj in enumerate(self):
-                 self.sos_sym_entries[sum_tuple(bi, bj)].append((i, j))
 
     def __len__(self) -> int:
         return len(self.monoms)
 
     def __iter__(self) -> Iterable[Tuple[int]]:
         return iter(self.monoms)
 
+    @property
+    @lru_cache()
+    def sos_sym_entries(self):
+        # A map from a monomial m (represented as tuple) to list of pairs (i, j)
+        # for all such pairs where m = basis[i]*basis[j].
+        sos_sym_entries = defaultdict(list)
+        for i, bi in enumerate(self):
+            for j, bj in enumerate(self):
+                 sos_sym_entries[sum_tuple(bi, bj)].append((i, j))
+        return sos_sym_entries
+
     def from_degree(nvars: int, deg: int, hom: bool=False) -> Basis:
         '''Constructs a basis by specifying the number of variables and degree'''
         return Basis(list((basis_hom if hom else basis_inhom)(nvars, deg)))