From 4c2daf59334f3a44311f84e26a8e48a5c9302a07 Mon Sep 17 00:00:00 2001
From: Magnus Ulimoen <magnus@ulimoen.dev>
Date: Fri, 29 Jan 2021 00:08:31 +0100
Subject: [PATCH] minor thingys

---
 sbp/src/operators/algos.rs        | 14 ++++++--------
 sbp/src/operators/traditional4.rs | 13 ++++++++++++-
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/sbp/src/operators/algos.rs b/sbp/src/operators/algos.rs
index 9717a98..917d9e0 100644
--- a/sbp/src/operators/algos.rs
+++ b/sbp/src/operators/algos.rs
@@ -3,6 +3,7 @@ use super::*;
 pub(crate) mod constmatrix {
     /// A row-major matrix
     #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
+    #[repr(transparent)]
     pub struct Matrix<T, const M: usize, const N: usize> {
         data: [[T; N]; M],
     }
@@ -94,12 +95,8 @@ pub(crate) mod constmatrix {
                 }
             }
         }
-        pub fn iter(&self) -> impl ExactSizeIterator<Item = &T> + DoubleEndedIterator<Item = &T> {
-            (0..N * M).map(move |x| {
-                let i = x / N;
-                let j = x % N;
-                &self[(i, j)]
-            })
+        pub fn iter(&self) -> impl Iterator<Item = &T> {
+            self.data.iter().flatten()
         }
         pub fn iter_mut(&mut self) -> impl Iterator<Item = &mut T> {
             self.data.iter_mut().flatten()
@@ -352,7 +349,8 @@ pub(crate) fn diff_op_1d_slice_matrix<const M: usize, const N: usize, const D: u
     } else {
         1.0 / (nx - 1) as Float
     };
-    let idx = FastFloat::from(1.0 / dx);
+    let idx = 1.0 / dx;
+    let idx = FastFloat::from(idx);
 
     use std::convert::TryInto;
     {
@@ -382,7 +380,7 @@ pub(crate) fn diff_op_1d_slice_matrix<const M: usize, const N: usize, const D: u
     }
 
     {
-        let prev = prev.array_windows::<N>().last().unwrap();
+        let prev = prev.array_windows::<N>().next_back().unwrap();
         let prev = ColVector::<_, N>::map_to_col(prev);
         let fut = ColVector::<_, M>::map_to_col_mut((&mut fut[nx - M..]).try_into().unwrap());
 
diff --git a/sbp/src/operators/traditional4.rs b/sbp/src/operators/traditional4.rs
index 4e5abad..352a92b 100644
--- a/sbp/src/operators/traditional4.rs
+++ b/sbp/src/operators/traditional4.rs
@@ -92,7 +92,7 @@ impl SbpOperator1d for SBP4 {
 fn diff_op_row_local(prev: ndarray::ArrayView2<Float>, mut fut: ndarray::ArrayViewMut2<Float>) {
     // Magic two lines that prevents or enables optimisation
     // (doubles instructions when not included)
-    let mut flipmatrix = SBP4::BLOCK_MATRIX.flip();
+    let mut flipmatrix = SBP4::BLOCK_MATRIX;
     flipmatrix *= &-1.0;
 
     for (p, mut f) in prev
@@ -228,3 +228,14 @@ fn test_trad4() {
         1e-1,
     );
 }
+
+#[test]
+fn block_equality() {
+    let mut flipped_inverted = SBP4::BLOCK_MATRIX.flip();
+    flipped_inverted *= &-1.0;
+
+    assert!(flipped_inverted
+        .iter()
+        .zip(SBP4::BLOCKEND_MATRIX.iter())
+        .all(|(x, y)| (x - y).abs() < 1e-3))
+}