Add constants file and introduce EPS for numerical precision

2 files changed, 12 insertions, 0 deletions

diff --git a/mdpoly/abc.py b/mdpoly/abc.py
index 53b16a5..7ac21dd 100644
--- a/mdpoly/abc.py
+++ b/mdpoly/abc.py
@@ -5,6 +5,7 @@ Defines:
   - Representations of polynomials
 """
 from .types import Number, Shape, MatrixIndex, PolyIndex
+from .constants import NUMERICS_EPS
 
 from typing import Self, Sequence, Protocol, runtime_checkable
 from abc import abstractmethod
@@ -60,6 +61,10 @@ class Repr(Protocol):
         """ Set value of polynomial entry """
 
     @abstractmethod
+    def set_zero(self, entry: MatrixIndex, term: PolyIndex) -> None:
+        """ Set an entry to zero """
+
+    @abstractmethod
     def entries(self) -> Sequence[MatrixIndex]:
         """ Return indices to non-zero entries of the matrix """
 
@@ -68,6 +73,12 @@ class Repr(Protocol):
         """ Return indices to non-zero terms in the polynomial at the given
         matrix entry """
 
+    def zero_smaller_than(self, eps: Number = NUMERICS_EPS) -> None:
+        for entry in self.entries():
+            for term in self.terms(entry):
+                if self.at(entry, term) < eps:
+                    self.set_zero(entry, term)
+
     def __iter__(self) -> Sequence[tuple[MatrixIndex, PolyIndex, Number]]:
         """ Iterate over non-zero entries of the representations """
         for entry in self.entries():
diff --git a/mdpoly/constants.py b/mdpoly/constants.py
new file mode 100644
index 0000000..2d62186
--- /dev/null
+++ b/mdpoly/constants.py
@@ -0,0 +1 @@
+NUMERICS_EPS = 1e-12