Improve docstring of index types

1 files changed, 22 insertions, 4 deletions

diff --git a/mdpoly/types.py b/mdpoly/types.py
index 14847fa..29e7b83 100644
--- a/mdpoly/types.py
+++ b/mdpoly/types.py
@@ -50,13 +50,31 @@ class MatrixIndex(NamedTuple):
         return cls(row, col)
 
 
-class PolyTermIndex(NamedTuple):
-    term: int
+class PolyVarIndex(NamedTuple):
+    """ 
+    Tuple to index a power of a variable.
+
+    Concretely this represents things like x^2, y^4
+    """
+    varindex: int
     power: Number
 
 
-class PolyIndex:
+class PolyIndex(tuple[PolyVarIndex]):
     """
     Tuple to index a coefficient of a polynomial.
+
+    Example: 
+
+        Suppose there are two variables x, y with indices 0, 1 respectively.
+        Then the monomal xy^2 has PolyIndex
+
+        (PolyVarIndex(varindex=0, power=1), PolyVarIndex(varindex=1, power=2)
+
+        Then given the polynomial
+
+            p(x, y) = 3x^2 + 5xy^2
+
+        The with the PolyIndex above we can retrieve the coefficient 5 in front
+        of xy^2.
     """
-    indices: tuple[PolyTermIndex]