fix a crash with fixed pervasive math

src/algorithm/mod.rs

@@ -162,7 +162,7 @@ where
  .all(|(b, a)| b == a)
  {
  a.shape.drain(..fixes);
- for &dim in b.shape[..fixes].iter().rev() {
+ for &dim in b.shape.iter().take(fixes).rev() {
  a.reshape_scalar(dim);
  }
  }
@@ -177,7 +177,7 @@ where
  .all(|(a, b)| a == b)
  {
  b.shape.drain(..fixes);
- for &dim in a.shape[..fixes].iter().rev() {
+ for &dim in a.shape.iter().take(fixes).rev() {
  b.reshape_scalar(dim);
  }
  }

tests/units.ua

@@ -18,6 +18,7 @@
 ⍤⊃⋅∘≍ [3_2_1 4_3_2 5_4_3] - ¤[1 2 3] [4 5 6]
 ⍤⊃⋅∘≍ 0_3 △ +¤ ↯3 0 ↯0_3 0
 ⍤⊃⋅∘≍ 1_3 △ +¤ ↯3 0 ↯1_3 0
+⍤⊃⋅∘≍ ⇡10 + ¤¤0 ⇡10
 
 # Filled pervasive math
 ⍤⊃⋅∘≍ [1_1 0_0] ⬚0↥ ↯ 2_2 0 ↯ 1_2 1