# HG changeset patch
# User Tuomo Valkonen <tuomov@iki.fi>
# Date 1757051339 18000
# Node ID b071a1b484f8811ce011f22d6bdc0055b6dad7e8
# Parent  21e51de02ab61cfb9cbbe8be1bff421c93ad2a0c
AXPY implementation reductions

diff -r 21e51de02ab6 -r b071a1b484f8 src/euclidean/wrap.rs
--- a/src/euclidean/wrap.rs	Fri Sep 05 00:16:08 2025 -0500
+++ b/src/euclidean/wrap.rs	Fri Sep 05 00:48:59 2025 -0500
@@ -148,7 +148,7 @@
         impl<$($qual)*> $crate::norms::Dist<$crate::norms::L2, $F> for $type
         {
             fn dist<I: $crate::instance::Instance<Self>>(&self, other : I, p : $crate::norms::L2) -> $F {
-                other.eval_ref(|x| self.get_view().dist(x, p))
+                other.eval_ref(|x| self.get_view().dist(x.get_view(), p))
             }
         }
 
@@ -226,19 +226,19 @@
         {
              fn axpy<I: $crate::instance::Instance<Self>>(&mut self, α: $F, x: I, β: $F) {
                 x.eval_decompose(|v| {
-                    self.get_view_mut().axpy(α, v.get_view(), β)
+                    self.get_view_mut().axpy(α, (*v).get_view(), β)
                 })
             }
 
             fn copy_from<I: $crate::instance::Instance<Self>>(&mut self, x: I) {
                 x.eval_decompose(|v| {
-                    self.get_view_mut().copy_from(&v.get_view())
+                    self.get_view_mut().copy_from((*v).get_view())
                 })
             }
 
             fn scale_from<I: $crate::instance::Instance<Self>>(&mut self, α: $F, x: I) {
                 x.eval_decompose(|v| {
-                    self.get_view_mut().scale_from(α, v.get_view())
+                    self.get_view_mut().scale_from(α, (*v).get_view())
                 })
             }
 
diff -r 21e51de02ab6 -r b071a1b484f8 src/linops.rs
--- a/src/linops.rs	Fri Sep 05 00:16:08 2025 -0500
+++ b/src/linops.rs	Fri Sep 05 00:48:59 2025 -0500
@@ -44,9 +44,13 @@
 
     /// Principal form of the space; always equal to [`Space::Principal`], but with
     /// more traits guaranteed.
+    ///
+    /// `PrincipalV` is only assumed to be `AXPY` for itself, as [`AXPY`]
+    /// uses [`Instance`] to apply all other variants and avoid problems
+    /// of choosing multiple implementations of the trait.
     type PrincipalV: ClosedSpace
         + AXPY<
-            Self,
+            Self::PrincipalV,
             Field = Self::Field,
             PrincipalV = Self::PrincipalV,
             OwnedVariant = Self::PrincipalV,
diff -r 21e51de02ab6 -r b071a1b484f8 src/nalgebra_support.rs
--- a/src/nalgebra_support.rs	Fri Sep 05 00:16:08 2025 -0500
+++ b/src/nalgebra_support.rs	Fri Sep 05 00:48:59 2025 -0500
@@ -359,10 +359,11 @@
     }
 }
 
-impl<SM, SV1, M, N, E> AXPY<Matrix<E, M, N, SV1>> for Matrix<E, M, N, SM>
+// This can only be implemented for the “principal” OMatrix as parameter, as otherwise
+// we run into problems of multiple implementations when calling the methods.
+impl<M, N, E, S> AXPY<OMatrix<E, M, N>> for Matrix<E, M, N, S>
 where
-    SM: StorageMut<E, M, N>,
-    SV1: Storage<E, M, N>,
+    S: StorageMut<E, M, N>,
     M: Dim,
     N: Dim,
     E: Scalar + Zero + One + Float,
@@ -370,7 +371,7 @@
     ShapeConstraint: StridesOk<E, M, N>,
 {
     #[inline]
-    fn axpy<I: Instance<Matrix<E, M, N, SV1>>>(&mut self, α: E, x: I, β: E) {
+    fn axpy<I: Instance<OMatrix<E, M, N>>>(&mut self, α: E, x: I, β: E) {
         x.eval(|x̃| {
             assert_eq!(self.ncols(), x̃.ncols());
             // nalgebra does not implement axpy for matrices, and flattenining
@@ -382,7 +383,7 @@
     }
 
     #[inline]
-    fn copy_from<I: Instance<Matrix<E, M, N, SV1>>>(&mut self, y: I) {
+    fn copy_from<I: Instance<OMatrix<E, M, N>>>(&mut self, y: I) {
         y.eval_ref(|ỹ| Matrix::copy_from(self, &ỹ))
     }