Resolved gh-444 by adding the new phpspreadsheet library, and removing the old PHPExcel library.

libraries/phpspreadsheet/vendor/markbaker/matrix/classes/src/Builder.php

@@ -0,0 +1,70 @@
+<?php
+
+/**
+ *
+ * Class for the creating "special" Matrices
+ *
+ * @copyright  Copyright (c) 2018 Mark Baker (https://github.com/MarkBaker/PHPMatrix)
+ * @license    https://opensource.org/licenses/MIT    MIT
+ */
+
+namespace Matrix;
+
+/**
+ * Matrix Builder class.
+ *
+ * @package Matrix
+ */
+class Builder
+{
+    /**
+     * Create a new matrix of specified dimensions, and filled with a specified value
+     * If the column argument isn't provided, then a square matrix will be created
+     *
+     * @param mixed $value
+     * @param int $rows
+     * @param int|null $columns
+     * @return Matrix
+     * @throws Exception
+     */
+    public static function createFilledMatrix($value, $rows, $columns = null)
+    {
+        if ($columns === null) {
+            $columns = $rows;
+        }
+
+        $rows = Matrix::validateRow($rows);
+        $columns = Matrix::validateColumn($columns);
+
+        return new Matrix(
+            array_fill(
+                0,
+                $rows,
+                array_fill(
+                    0,
+                    $columns,
+                    $value
+                )
+            )
+        );
+    }
+
+    /**
+     * Create a new identity matrix of specified dimensions
+     * This will always be a square matrix, with the number of rows and columns matching the provided dimension
+     *
+     * @param int $dimensions
+     * @return Matrix
+     * @throws Exception
+     */
+    public static function createIdentityMatrix($dimensions)
+    {
+        $grid = static::createFilledMatrix(null, $dimensions)->toArray();
+
+        for ($x = 0; $x < $dimensions; ++$x) {
+            $grid[$x][$x] = 1;
+        }
+
+        return new Matrix($grid);
+    }
+}