From db4dac3de9c67d20c0e866997a763fc5bac4ba21 Mon Sep 17 00:00:00 2001
From: MarkBaker <mark@lange.demon.co.uk>
Date: Tue, 17 May 2022 16:40:14 +0200
Subject: [PATCH] Filter null values in PRODUCT() function, as they don't
 affect the calculation in any way, and actually require additional code
 handling if they're present within the calculation itself

---
 .../Calculation/MathTrig/Operations.php       | 26 +++++++++----------
 tests/data/Calculation/MathTrig/PRODUCT.php   | 16 ++++++++++--
 2 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/src/PhpSpreadsheet/Calculation/MathTrig/Operations.php b/src/PhpSpreadsheet/Calculation/MathTrig/Operations.php
index 44e13526..f26da389 100644
--- a/src/PhpSpreadsheet/Calculation/MathTrig/Operations.php
+++ b/src/PhpSpreadsheet/Calculation/MathTrig/Operations.php
@@ -102,29 +102,27 @@ class Operations
      */
     public static function product(...$args)
     {
+        $args = array_filter(
+            Functions::flattenArray($args),
+            function ($value) {
+                return $value !== null;
+            }
+        );
+
         // Return value
-        $returnValue = null;
+        $returnValue = (count($args) === 0) ? 0.0 : 1.0;
 
         // Loop through arguments
-        foreach (Functions::flattenArray($args) as $arg) {
+        foreach ($args as $arg) {
             // Is it a numeric value?
-            if (is_numeric($arg) || $arg === null) {
-                if ($returnValue === null) {
-                    $returnValue = $arg;
-                } else {
-                    $returnValue *= $arg;
-                }
+            if (is_numeric($arg)) {
+                $returnValue *= $arg;
             } else {
                 return ExcelError::VALUE();
             }
         }
 
-        // Return
-        if ($returnValue === null) {
-            return 0;
-        }
-
-        return $returnValue;
+        return (float) $returnValue;
     }
 
     /**
diff --git a/tests/data/Calculation/MathTrig/PRODUCT.php b/tests/data/Calculation/MathTrig/PRODUCT.php
index ab500953..657c713c 100644
--- a/tests/data/Calculation/MathTrig/PRODUCT.php
+++ b/tests/data/Calculation/MathTrig/PRODUCT.php
@@ -49,17 +49,29 @@ return [
         -2,
     ],
     [
-        0,
+        31.25,
         12.5,
         null,
         2.5,
     ],
     [
-        0,
+        31.25,
         12.5,
         2.5,
         null,
     ],
+    [
+        12.5,
+        12.5,
+        null,
+        null,
+    ],
+    [
+        0.0,
+        null,
+        null,
+        null,
+    ],
     ['#VALUE!', 1, 'y', 3],
     [6, 1, '2', 3],
 ];