From 1c274b3ee78efc413a439de5e9a65ad9b658571c Mon Sep 17 00:00:00 2001
From: Vincent Esche <regexident@gmail.com>
Date: Mon, 23 Sep 2019 13:45:42 +0200
Subject: [PATCH] Added `Matrix += Matrix` and turned `Matrix + Matrix` into a
 shallow wrapper around it

---
 Sources/Surge/Linear Algebra/Matrix.swift | 46 ++++++++++++++++++++---
 1 file changed, 41 insertions(+), 5 deletions(-)

diff --git a/Sources/Surge/Linear Algebra/Matrix.swift b/Sources/Surge/Linear Algebra/Matrix.swift
index aa3bc61..ce7227e 100644
--- a/Sources/Surge/Linear Algebra/Matrix.swift	
+++ b/Sources/Surge/Linear Algebra/Matrix.swift	
@@ -269,12 +269,10 @@ public func ==<T> (lhs: Matrix<T>, rhs: Matrix<T>) -> Bool {
 public func add(_ lhs: Matrix<Float>, _ rhs: Matrix<Float>) -> Matrix<Float> {
     precondition(lhs.rows == rhs.rows && lhs.columns == rhs.columns, "Matrix dimensions not compatible with addition")
 
-    var results = rhs
-    results.grid.withUnsafeMutableBufferPointer { pointer in
-        cblas_saxpy(Int32(lhs.grid.count), 1.0, lhs.grid, 1, pointer.baseAddress!, 1)
-    }
+    var result = lhs
+    result += rhs
 
-    return results
+    return result
 }
 
 public func add(_ lhs: Matrix<Double>, _ rhs: Matrix<Double>) -> Matrix<Double> {
@@ -296,6 +294,44 @@ public func + (lhs: Matrix<Double>, rhs: Matrix<Double>) -> Matrix<Double> {
     return add(lhs, rhs)
 }
 
+// MARK: - Addition: In Place
+
+func addInPlace(_ lhs: inout Matrix<Float>, _ rhs: Matrix<Float>) {
+    precondition(lhs.rows == rhs.rows && lhs.columns == rhs.columns, "Matrix dimensions not compatible with addition")
+
+    let gridSize = Int32(lhs.grid.count)
+    let alpha: Float = 1.0
+    let stride: Int32 = 1
+
+    lhs.grid.withUnsafeMutableBufferPointer { lhsPointer in
+        rhs.grid.withUnsafeBufferPointer { rhsPointer in
+            cblas_saxpy(gridSize, alpha, rhsPointer.baseAddress!, stride, lhsPointer.baseAddress!, stride)
+        }
+    }
+}
+
+func addInPlace(_ lhs: inout Matrix<Double>, _ rhs: Matrix<Double>) {
+    precondition(lhs.rows == rhs.rows && lhs.columns == rhs.columns, "Matrix dimensions not compatible with addition")
+
+    let gridSize = Int32(lhs.grid.count)
+    let alpha: Double = 1.0
+    let stride: Int32 = 1
+
+    lhs.grid.withUnsafeMutableBufferPointer { lhsPointer in
+        rhs.grid.withUnsafeBufferPointer { rhsPointer in
+            cblas_daxpy(gridSize, alpha, rhsPointer.baseAddress!, stride, lhsPointer.baseAddress!, stride)
+        }
+    }
+}
+
+public func += (lhs: inout Matrix<Float>, rhs: Matrix<Float>) {
+    return addInPlace(&lhs, rhs)
+}
+
+public func += (lhs: inout Matrix<Double>, rhs: Matrix<Double>) {
+    return addInPlace(&lhs, rhs)
+}
+
 // MARK: - Subtraction
 
 public func sub(_ lhs: Matrix<Float>, _ rhs: Matrix<Float>) -> Matrix<Float> {