diff -r 4c2e5e65d510 -r f2fc6115b897 src/direct_product.rs
--- a/src/direct_product.rs	Tue Dec 31 23:34:47 2024 -0500
+++ b/src/direct_product.rs	Tue Dec 31 23:49:09 2024 -0500
@@ -282,12 +282,9 @@
     F : Num,
     Self : MulAssign<F>,
     Pair<A, B> :  MulAssign<F>,
-    Pair<A::Owned, B::Owned> : AXPY<F, Pair<U, V>>,
 {
 
-    type Owned = Pair<A::Owned, B::Owned>;
-
-    fn add_mul<I : Instance<Pair<U,V>>>(self, α : F, x : I, β : F) -> Self::Owned {
+    fn add_mul<I : Instance<Pair<U,V>>>(self, α : F, x : I, β : F) -> Pair<U, V> {
         let Pair(u, v) = x.decompose();
         Pair(self.0.add_mul(α, u, β), self.1.add_mul(α, v, β))
     }
@@ -311,7 +308,7 @@
     }
 
     /// Return a similar zero as `self`.
-    fn similar_origin(&self) -> Self::Owned {
+    fn similar_origin(&self) -> Pair<U, V> {
         Pair(self.0.similar_origin(), self.1.similar_origin())
     }