From b0e1ec62f86b3e19a98cdc066b3288fcd74be8bb Mon Sep 17 00:00:00 2001
From: Magnus Ulimoen <magnus@ulimoen.dev>
Date: Sun, 31 Jan 2021 13:23:15 +0100
Subject: [PATCH] change order in matmul_into

---
 sbp/src/operators/algos.rs | 72 +++++++++++++++++++++++---------------
 1 file changed, 43 insertions(+), 29 deletions(-)

diff --git a/sbp/src/operators/algos.rs b/sbp/src/operators/algos.rs
index 1928f2d..1681501 100644
--- a/sbp/src/operators/algos.rs
+++ b/sbp/src/operators/algos.rs
@@ -61,31 +61,6 @@ pub(crate) mod constmatrix {
         pub const fn ncols(&self) -> usize {
             N
         }
-        pub fn matmul<const P: usize>(&self, other: &Matrix<T, N, P>) -> Matrix<T, M, P>
-        where
-            T: Copy + Default + core::ops::Add<Output = T> + core::ops::Mul<Output = T>,
-        {
-            let mut out = Matrix::default();
-            self.matmul_into(other, &mut out);
-            out
-        }
-        pub fn matmul_into<const P: usize>(
-            &self,
-            other: &Matrix<T, N, P>,
-            out: &mut Matrix<T, M, P>,
-        ) where
-            T: Copy + Default + core::ops::Add<Output = T> + core::ops::Mul<Output = T>,
-        {
-            for i in 0..M {
-                for j in 0..P {
-                    let mut t = T::default();
-                    for k in 0..N {
-                        t = t + self[(i, k)] * other[(k, j)];
-                    }
-                    out[(i, j)] = t;
-                }
-            }
-        }
         #[inline(always)]
         pub fn iter(&self) -> impl Iterator<Item = &T> {
             self.data.iter().flatten()
@@ -135,6 +110,45 @@ pub(crate) mod constmatrix {
         }
     }
 
+    impl<T, const M: usize, const P: usize> Matrix<T, M, P> {
+        #[inline(always)]
+        pub fn matmul_into<const N: usize>(&mut self, lhs: &Matrix<T, M, N>, rhs: &Matrix<T, N, P>)
+        where
+            T: Default + Copy + core::ops::Mul<Output = T> + core::ops::Add<Output = T>,
+        {
+            for i in 0..M {
+                for j in 0..P {
+                    let mut t = T::default();
+                    for k in 0..N {
+                        t = t + lhs[(i, k)] * rhs[(k, j)];
+                    }
+                    self[(i, j)] = t;
+                }
+            }
+        }
+    }
+
+    macro_rules! impl_op_mul_mul {
+        ($lhs:ty, $rhs:ty) => {
+            impl<T, const N: usize, const M: usize, const P: usize> core::ops::Mul<$rhs> for $lhs
+            where
+                T: Copy + Default + core::ops::Add<Output = T> + core::ops::Mul<Output = T>,
+            {
+                type Output = Matrix<T, M, P>;
+                fn mul(self, rhs: $rhs) -> Self::Output {
+                    let mut out = Matrix::default();
+                    out.matmul_into(&self, &rhs);
+                    out
+                }
+            }
+        };
+    }
+
+    impl_op_mul_mul! {  Matrix<T, M, N>,  Matrix<T, N, P> }
+    impl_op_mul_mul! { &Matrix<T, M, N>,  Matrix<T, N, P> }
+    impl_op_mul_mul! {  Matrix<T, M, N>, &Matrix<T, N, P> }
+    impl_op_mul_mul! { &Matrix<T, M, N>, &Matrix<T, N, P> }
+
     impl<T, const M: usize, const N: usize> core::ops::MulAssign<T> for Matrix<T, M, N>
     where
         T: Copy + core::ops::MulAssign<T>,
@@ -161,7 +175,7 @@ pub(crate) mod constmatrix {
             let m1 = Matrix::new([[1_u8, 2, 3], [4, 5, 6]]);
             let m2 = Matrix::new([[7_u8, 8, 9, 10], [11, 12, 13, 14], [15, 16, 17, 18]]);
 
-            let m3 = m1.matmul(&m2);
+            let m3 = m1 * m2;
             assert_eq!(m3, Matrix::new([[74, 80, 86, 92], [173, 188, 203, 218]]));
         }
     }
@@ -325,7 +339,7 @@ pub(crate) fn diff_op_1d_slice_matrix<const M: usize, const N: usize, const D: u
         let prev = ColVector::<_, N>::map_to_col(prev.array_windows::<N>().next().unwrap());
         let fut = ColVector::<_, M>::map_to_col_mut(futb1.try_into().unwrap());
 
-        block.matmul_into(prev, fut);
+        fut.matmul_into(block, prev);
         *fut *= idx;
     }
 
@@ -341,7 +355,7 @@ pub(crate) fn diff_op_1d_slice_matrix<const M: usize, const N: usize, const D: u
         let fut = ColVector::<_, 1>::map_to_col_mut(f);
         let prev = ColVector::<_, D>::map_to_col(window);
 
-        diag.matmul_into(prev, fut);
+        fut.matmul_into(diag, prev);
         *fut *= idx;
     }
 
@@ -350,7 +364,7 @@ pub(crate) fn diff_op_1d_slice_matrix<const M: usize, const N: usize, const D: u
         let prev = ColVector::<_, N>::map_to_col(prev);
         let fut = ColVector::<_, M>::map_to_col_mut(futb2.try_into().unwrap());
 
-        endblock.matmul_into(prev, fut);
+        fut.matmul_into(endblock, prev);
         *fut *= idx;
     }
 }