From 1f9f97f8d9bd073e423bf2792167e04cde663a5f Mon Sep 17 00:00:00 2001
From: Dennis Eichhorn <spl1nnes.com@googlemail.com>
Date: Sun, 22 Oct 2023 17:19:44 +0000
Subject: [PATCH] fix matrix exp and cosine metric

---
 Math/Matrix/Matrix.php      | 7 +++----
 Math/Topology/MetricsND.php | 4 ++--
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/Math/Matrix/Matrix.php b/Math/Matrix/Matrix.php
index 21c8907f7..402cbb4ae 100755
--- a/Math/Matrix/Matrix.php
+++ b/Math/Matrix/Matrix.php
@@ -917,15 +917,14 @@ class Matrix implements \ArrayAccess, \Iterator
         $matrix   = $identity;
 
         $factorial = 1;
-        $pow       = $matrix;
+        $pow       = clone $matrix;
 
         for ($i = 1; $i <= $iterations; ++$i) {
             $factorial *= $i;
             $coeff      = 1 / $factorial;
 
-            $term   = $pow->mult($coeff);
-            $matrix = $matrix->add($term);
-            $pow    = $pow->mult($matrix); // @todo: maybe wrong order?
+            $term   = clone $pow->mult($this);
+            $matrix = $matrix->add($term->mult($coeff));
         }
 
         return $matrix;
diff --git a/Math/Topology/MetricsND.php b/Math/Topology/MetricsND.php
index fd36db66f..aa9b0969f 100755
--- a/Math/Topology/MetricsND.php
+++ b/Math/Topology/MetricsND.php
@@ -111,8 +111,8 @@ final class MetricsND
         }
 
         $dotProduct = 0;
-        for ($i = 0; $i < $length; ++$i) {
-            $dotProduct += $a[$i] * $b[$i];
+        foreach ($a as $id => $_) {
+            $dotProduct += $a[$id] * $b[$id];
         }
 
         $sumOfSquares = 0;