From ba41a8ce5ab5987d138d02205c908635053eb62a Mon Sep 17 00:00:00 2001
From: Brendan Zabarauskas <bjzaba@yahoo.com.au>
Date: Sun, 2 Jul 2017 01:22:47 +1000
Subject: [PATCH] Implement the sum and product traits for matrices

Closes #264
---
 src/core/ops.rs | 46 +++++++++++++++++++++++++++++++++++++++++++---
 tests/matrix.rs | 41 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+), 3 deletions(-)

diff --git a/src/core/ops.rs b/src/core/ops.rs
index a530e066..98c0186f 100644
--- a/src/core/ops.rs
+++ b/src/core/ops.rs
@@ -1,11 +1,12 @@
+use std::iter;
 use std::ops::{Add, AddAssign, Sub, SubAssign, Mul, MulAssign, Div, DivAssign, Neg,
                Index, IndexMut};
-use num::Zero;
+use num::{Zero, One};
 
 use alga::general::{ClosedMul, ClosedDiv, ClosedAdd, ClosedSub, ClosedNeg};
 
-use core::{Scalar, Matrix, OwnedMatrix, MatrixSum, MatrixMul, MatrixTrMul};
-use core::dimension::{Dim, DimMul, DimProd};
+use core::{Scalar, Matrix, OwnedMatrix, SquareMatrix, MatrixSum, MatrixMul, MatrixTrMul};
+use core::dimension::{Dim, DimMul, DimName, DimProd};
 use core::constraint::{ShapeConstraint, SameNumberOfRows, SameNumberOfColumns, AreMultipliable};
 use core::storage::{Storage, StorageMut, OwnedStorage};
 use core::allocator::{SameShapeAllocator, Allocator, OwnedAllocator};
@@ -231,6 +232,25 @@ macro_rules! componentwise_binop_impl(
 componentwise_binop_impl!(Add, add, ClosedAdd; AddAssign, add_assign);
 componentwise_binop_impl!(Sub, sub, ClosedSub; SubAssign, sub_assign);
 
+impl<N, R: DimName, C: DimName, S> iter::Sum for Matrix<N, R, C, S>
+    where N: Scalar + ClosedAdd + Zero,
+          S: OwnedStorage<N, R, C>,
+          S::Alloc: OwnedAllocator<N, R, C, S>
+{
+    fn sum<I: Iterator<Item = Matrix<N, R, C, S>>>(iter: I) -> Matrix<N, R, C, S> {
+        iter.fold(Matrix::zero(), |acc, x| acc + x)
+    }
+}
+
+impl<'a, N, R: DimName, C: DimName, S> iter::Sum<&'a Matrix<N, R, C, S>> for Matrix<N, R, C, S>
+    where N: Scalar + ClosedAdd + Zero,
+          S: OwnedStorage<N, R, C>,
+          S::Alloc: OwnedAllocator<N, R, C, S>
+{
+    fn sum<I: Iterator<Item = &'a Matrix<N, R, C, S>>>(iter: I) -> Matrix<N, R, C, S> {
+        iter.fold(Matrix::zero(), |acc, x| acc + x)
+    }
+}
 
 
 /*
@@ -528,3 +548,23 @@ impl<N, R1: Dim, C1: Dim, SA> Matrix<N, R1, C1, SA>
         res
     }
 }
+
+impl<N, D: DimName, S> iter::Product for SquareMatrix<N, D, S>
+    where N: Scalar + Zero + One + ClosedMul + ClosedAdd,
+          S: OwnedStorage<N, D, D>,
+          S::Alloc: OwnedAllocator<N, D, D, S>
+{
+    fn product<I: Iterator<Item = SquareMatrix<N, D, S>>>(iter: I) -> SquareMatrix<N, D, S> {
+        iter.fold(Matrix::one(), |acc, x| acc * x)
+    }
+}
+
+impl<'a, N, D: DimName, S> iter::Product<&'a SquareMatrix<N, D, S>> for SquareMatrix<N, D, S>
+    where N: Scalar + Zero + One + ClosedMul + ClosedAdd,
+          S: OwnedStorage<N, D, D>,
+          S::Alloc: OwnedAllocator<N, D, D, S>
+{
+    fn product<I: Iterator<Item = &'a SquareMatrix<N, D, S>>>(iter: I) -> SquareMatrix<N, D, S> {
+        iter.fold(Matrix::one(), |acc, x| acc * x)
+    }
+}
diff --git a/tests/matrix.rs b/tests/matrix.rs
index 2b319498..b41b1e34 100644
--- a/tests/matrix.rs
+++ b/tests/matrix.rs
@@ -263,6 +263,25 @@ fn simple_add() {
     assert_eq!(expected, &c +  a);
 }
 
+#[test]
+fn simple_sum() {
+    type M = Matrix2x3<f32>;
+
+    let a = M::new(1.0, 2.0, 3.0,
+                   4.0, 5.0, 6.0);
+    let b = M::new(10.0, 20.0, 30.0,
+                   40.0, 50.0, 60.0);
+    let c = M::new(100.0, 200.0, 300.0,
+                   400.0, 500.0, 600.0);
+
+    assert_eq!(M::zero(), Vec::<M>::new().iter().sum());
+    assert_eq!(M::zero(), Vec::<M>::new().into_iter().sum());
+    assert_eq!(a + b, vec![a, b].iter().sum());
+    assert_eq!(a + b, vec![a, b].into_iter().sum());
+    assert_eq!(a + b + c, vec![a, b, c].iter().sum());
+    assert_eq!(a + b + c, vec![a, b, c].into_iter().sum());
+}
+
 #[test]
 fn simple_scalar_mul() {
     let a = Matrix2x3::new(1.0, 2.0, 3.0,
@@ -295,6 +314,28 @@ fn simple_mul() {
     assert_eq!(expected,  a *  b);
 }
 
+#[test]
+fn simple_product() {
+    type M = Matrix3<f32>;
+
+    let a = M::new(1.0, 2.0, 3.0,
+                   4.0, 5.0, 6.0,
+                   7.0, 8.0, 9.0);
+    let b = M::new(10.0, 20.0, 30.0,
+                   40.0, 50.0, 60.0,
+                   70.0, 80.0, 90.0);
+    let c = M::new(100.0, 200.0, 300.0,
+                   400.0, 500.0, 600.0,
+                   700.0, 800.0, 900.0);
+
+    assert_eq!(M::one(), Vec::<M>::new().iter().product());
+    assert_eq!(M::one(), Vec::<M>::new().into_iter().product());
+    assert_eq!(a * b, vec![a, b].iter().product());
+    assert_eq!(a * b, vec![a, b].into_iter().product());
+    assert_eq!(a * b * c, vec![a, b, c].iter().product());
+    assert_eq!(a * b * c, vec![a, b, c].into_iter().product());
+}
+
 #[test]
 fn simple_scalar_conversion() {
     let a = Matrix2x3::new(1.0, 2.0, 3.0,