rename and comment monomial_to_monomial_vector_indices

2 files changed, 15 insertions, 4 deletions

diff --git a/polymatrix/denserepr/from_.py b/polymatrix/denserepr/from_.py
index 7936c97..1eda6fe 100644
--- a/polymatrix/denserepr/from_.py
+++ b/polymatrix/denserepr/from_.py
@@ -9,7 +9,7 @@ from polymatrix.expression.mixins.expressionbasemixin import ExpressionBaseMixin
 from polymatrix.expression.utils.getvariableindices import (
     get_variable_indices_from_variable,
 )
-from polymatrix.denserepr.utils.monomialtoindex import variable_indices_to_column_index
+from polymatrix.denserepr.utils.monomialtoindex import monomial_to_monomial_vector_indices
 from polymatrix.denserepr.impl import DenseReprBufferImpl, DenseReprImpl
 
 # NP: create a dense representation from a polymatrix expression
@@ -150,7 +150,7 @@ def from_polymatrix(
                             # converts (2, 1) to (1, 2)
                             # converts (1, 2) to (3,)
                             # the cols correspond to the column of the dense matrix w.r.t. Z
-                            cols = variable_indices_to_column_index(
+                            cols = monomial_to_monomial_vector_indices(
                                 n_param, new_variable_indices
                             )
 
diff --git a/polymatrix/denserepr/utils/monomialtoindex.py b/polymatrix/denserepr/utils/monomialtoindex.py
index a41b9fc..151e8bf 100644
--- a/polymatrix/denserepr/utils/monomialtoindex.py
+++ b/polymatrix/denserepr/utils/monomialtoindex.py
@@ -2,10 +2,21 @@ import itertools
 
 
 # NP: document this function, especially magic return line
-def variable_indices_to_column_index(
+def monomial_to_monomial_vector_indices(
     n_var: int,
     variable_indices: tuple[int, ...],
-) -> int:
+) -> set[int]:
+    """
+    Given a monomial of degree d, this function returns the indices of a monomial
+    vector containing monomial of the same degree.
+    
+    Given the variable mapping {x : 0, y : 1}, the monomial x*y of the monomial vector
+
+        z = [x**2 x*y x*y y**2]
+
+    results in indices = (1, 2).    
+    """
+    
     variable_indices_perm = itertools.permutations(variable_indices)
 
     return set(