Merge pull request #890 from rust-ndarray/jt-scalar-ops-improvement

Scalar + &array and &array + scalar performance improvements

Author: bluss

benches/bench1.rs

@@ -433,6 +433,22 @@ fn scalar_add_2(bench: &mut test::Bencher) {
     bench.iter(|| n + &a);
 }
 
+#[bench]
+fn scalar_add_strided_1(bench: &mut test::Bencher) {
+    let a =
+        Array::from_shape_fn((64, 64 * 2), |(i, j)| (i * 64 + j) as f32).slice_move(s![.., ..;2]);
+    let n = 1.;
+    bench.iter(|| &a + n);
+}
+
+#[bench]
+fn scalar_add_strided_2(bench: &mut test::Bencher) {
+    let a =
+        Array::from_shape_fn((64, 64 * 2), |(i, j)| (i * 64 + j) as f32).slice_move(s![.., ..;2]);
+    let n = 1.;
+    bench.iter(|| n + &a);
+}
+
 #[bench]
 fn scalar_sub_1(bench: &mut test::Bencher) {
     let a = Array::<f32, _>::zeros((64, 64));

src/impl_ops.rs

@@ -159,8 +159,8 @@ impl<'a, A, S, D, B> $trt<B> for &'a ArrayBase<S, D>
           B: ScalarOperand,
 {
     type Output = Array<A, D>;
-    fn $mth(self, x: B) -> Array<A, D> {
-        self.to_owned().$mth(x)
+    fn $mth(self, x: B) -> Self::Output {
+        self.map(move |elt| elt.clone() $operator x.clone())
     }
 }
     );
@@ -210,11 +210,11 @@ impl<'a, S, D> $trt<&'a ArrayBase<S, D>> for $scalar
           D: Dimension,
 {
     type Output = Array<$scalar, D>;
-    fn $mth(self, rhs: &ArrayBase<S, D>) -> Array<$scalar, D> {
+    fn $mth(self, rhs: &ArrayBase<S, D>) -> Self::Output {
         if_commutative!($commutative {
             rhs.$mth(self)
         } or {
-            self.$mth(rhs.to_owned())
+            rhs.map(move |elt| self.clone() $operator elt.clone())
         })
     }
 }