1 files changed, 62 insertions, 0 deletions
diff --git a/polymatrix/expression/mixins/parametrizematrixexprmixin.py b/polymatrix/expression/mixins/parametrizematrixexprmixin.py
new file mode 100644
index 0000000..f59ddb7
--- /dev/null
+++ b/polymatrix/expression/mixins/parametrizematrixexprmixin.py
@@ -0,0 +1,62 @@
+
+import abc
+import dataclasses
+
+from polymatrix.polymatrix.init.initpolymatrix import init_poly_matrix
+from polymatrix.expression.mixins.expressionbasemixin import ExpressionBaseMixin
+from polymatrix.expressionstate.mixins.expressionstatemixin import ExpressionStateMixin
+from polymatrix.polymatrix.mixins.polymatrixmixin import PolyMatrixMixin
+
+
+# rename ParametrizeSymmetricMatrixExprMixin
+class ParametrizeMatrixExprMixin(ExpressionBaseMixin):
+    @property
+    @abc.abstractclassmethod
+    def underlying(self) -> ExpressionBaseMixin:
+        ...
+
+    @property
+    @abc.abstractclassmethod
+    def name(self) -> str:
+        ...
+
+    # overwrites abstract method of `ExpressionBaseMixin`
+    def apply(
+        self, 
+        state: ExpressionStateMixin,
+    ) -> tuple[ExpressionStateMixin, PolyMatrixMixin]:
+
+        # cache polymatrix to not re-parametrize at every apply call
+        if self in state.cache:
+            return state, state.cache[self]
+
+        state, underlying = self.underlying.apply(state)
+
+        assert underlying.shape[1] == 1
+
+        terms = {}
+        var_index = 0
+
+        for row in range(underlying.shape[0]):
+            for _ in range(row, underlying.shape[0]):
+                
+                terms[var_index, 0] = {((state.n_param + var_index, 1),): 1.0}
+
+                var_index += 1
+
+        state = state.register(
+            key=self, 
+            n_param=var_index,
+        )
+
+        poly_matrix = init_poly_matrix(
+            terms=terms,
+            shape=(var_index, 1),
+        )
+
+        state = dataclasses.replace(
+            state, 
+            cache=state.cache | {self: poly_matrix},
+        )
+
+        return state, poly_matrix