1 files changed, 35 insertions, 9 deletions

diff --git a/polymatrix/expression/mixins/additionexprmixin.py b/polymatrix/expression/mixins/additionexprmixin.py
index d274f2a..2c7a652 100644
--- a/polymatrix/expression/mixins/additionexprmixin.py
+++ b/polymatrix/expression/mixins/additionexprmixin.py
@@ -5,6 +5,7 @@ import dataclass_abc
 
 from polymatrix.expression.init.initpolymatrix import init_poly_matrix
 from polymatrix.expression.mixins.expressionbasemixin import ExpressionBaseMixin
+from polymatrix.expression.mixins.polymatrixmixin import PolyMatrixMixin
 from polymatrix.expression.polymatrix import PolyMatrix
 from polymatrix.expression.expressionstate import ExpressionState
 
@@ -20,24 +21,49 @@ class AdditionExprMixin(ExpressionBaseMixin):
     def right(self) -> ExpressionBaseMixin:
         ...
 
-    # # overwrites abstract method of `ExpressionBaseMixin`
-    # @property
-    # def shape(self) -> tuple[int, int]:
-    #     return self.left.shape
-
     # overwrites abstract method of `ExpressionBaseMixin`
-    def _apply(
+    def apply(
         self, 
         state: ExpressionState,
     ) -> tuple[ExpressionState, PolyMatrix]:
         state, left = self.left.apply(state=state)
         state, right = self.right.apply(state=state)
 
-        assert left.shape == right.shape, f'{left.shape} != {right.shape}'
-
         terms = {}
 
-        for underlying in (left, right):
+        if left.shape == (1, 1):
+            left, right = right, left
+
+        if left.shape != (1, 1) and right.shape == (1, 1):
+
+            @dataclass_abc.dataclass_abc(frozen=True)
+            class BroadCastedPolyMatrix(PolyMatrixMixin):
+                underlying_monomials: tuple[tuple[int], float]
+                shape: tuple[int, int]
+
+                def get_poly(self, row: int, col: int) -> typing.Optional[dict[tuple[int, ...], float]]:
+                    return self.underlying_monomials
+
+            try:
+                underlying_terms = right.get_poly(0, 0)
+
+            except KeyError:
+                pass
+
+            else:
+                broadcasted_right = BroadCastedPolyMatrix(
+                    underlying_monomials=underlying_terms,
+                    shape=left.shape,
+                )
+
+                all_underlying = (left, broadcasted_right)
+
+        else:
+            assert left.shape == right.shape, f'{left.shape} != {right.shape}'
+
+            all_underlying = (left, right)
+
+        for underlying in all_underlying:
 
             for row in range(left.shape[0]):
                 for col in range(left.shape[1]):