diff -r bd924d62d952 -r a0db98c16ab5 src/bisection_tree/btfn.rs
--- a/src/bisection_tree/btfn.rs	Wed Nov 06 15:34:17 2024 -0500
+++ b/src/bisection_tree/btfn.rs	Sat Nov 09 20:36:23 2024 -0500
@@ -424,12 +424,12 @@
 for BTFN<F, G, BT, N>
 where BT : BTImpl<F, N>,
       G : SupportGenerator<F, N, Id=BT::Data>,
-      G::SupportType : LocalAnalysis<F, BT::Agg, N> + Differentiable<&'a Loc<F, N>, Output = V>,
+      G::SupportType : LocalAnalysis<F, BT::Agg, N> + Differentiable<&'a Loc<F, N>, Derivative = V>,
       V : Sum {
 
-    type Output = V;
+    type Derivative = V;
 
-    fn differential(&self, x : &'a Loc<F, N>) -> Self::Output {
+    fn differential(&self, x : &'a Loc<F, N>) -> Self::Derivative {
         self.bt.iter_at(x)
             .map(|&d| self.generator.support_for(d).differential(x))
             .sum()
@@ -440,12 +440,12 @@
 for BTFN<F, G, BT, N>
 where BT : BTImpl<F, N>,
       G : SupportGenerator<F, N, Id=BT::Data>,
-      G::SupportType : LocalAnalysis<F, BT::Agg, N> + Differentiable<Loc<F, N>, Output = V>,
+      G::SupportType : LocalAnalysis<F, BT::Agg, N> + Differentiable<Loc<F, N>, Derivative = V>,
       V : Sum {
 
-    type Output = V;
+    type Derivative = V;
 
-    fn differential(&self, x : Loc<F, N>) -> Self::Output {
+    fn differential(&self, x : Loc<F, N>) -> Self::Derivative {
         self.bt.iter_at(&x)
             .map(|&d| self.generator.support_for(d).differential(x))
             .sum()