prep for 2023. Fixed many bugs. Added pdf guide

vendor/markbaker/matrix/classes/src/operations/directsum.php

@@ -0,0 +1,39 @@
+<?php
+
+/**
+ *
+ * Function code for the matrix direct sum operation
+ *
+ * @copyright  Copyright (c) 2018 Mark Baker (https://github.com/MarkBaker/PHPMatrix)
+ * @license    https://opensource.org/licenses/MIT    MIT
+ */
+namespace Matrix;
+
+use Matrix\Operators\DirectSum;
+
+/**
+ * Adds two or more matrices
+ *
+ * @param     mixed[]    $matrixValues   The matrices to add
+ * @return    Matrix
+ * @throws    Exception
+ */
+function directsum(...$matrixValues)
+{
+    if (count($matrixValues) < 2) {
+        throw new Exception('This operation requires at least 2 arguments');
+    }
+
+    $matrix = array_shift($matrixValues);
+    if (!is_object($matrix) || !($matrix instanceof Matrix)) {
+        $matrix = new Matrix($matrix);
+    }
+
+    $result = new DirectSum($matrix);
+
+    foreach ($matrixValues as $matrix) {
+        $result->execute($matrix);
+    }
+
+    return $result->result();
+}