From 8ac86cb254228d9faaa9d23e9936e840ef7d4dc3 Mon Sep 17 00:00:00 2001
From: Stephen Sweetland <steve.sweetland@gmail.com>
Date: Thu, 25 May 2017 11:07:36 +0100
Subject: [PATCH] Update Worksheet.php

Supporting *writing* formulas in XLSX files is truly trivial.
---
 src/Spout/Writer/XLSX/Internal/Worksheet.php | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/src/Spout/Writer/XLSX/Internal/Worksheet.php b/src/Spout/Writer/XLSX/Internal/Worksheet.php
index b5a3dc7..1d853e6 100644
--- a/src/Spout/Writer/XLSX/Internal/Worksheet.php
+++ b/src/Spout/Writer/XLSX/Internal/Worksheet.php
@@ -212,8 +212,10 @@ EOD;
         $columnIndex = CellHelper::getCellIndexFromColumnIndex($cellNumber);
         $cellXML = '<c r="' . $columnIndex . $rowIndex . '"';
         $cellXML .= ' s="' . $styleId . '"';
-
-        if (CellHelper::isNonEmptyString($cellValue)) {
+        
+        if (CellHelper::isFormulaString($cellValue)) {
+            $cellXML .= '><f>'.substr($cellValue,1).'</f><v>0</v></c>'; // seriously, that's it.
+        } else if (CellHelper::isNonEmptyString($cellValue)) {
             $cellXML .= $this->getCellXMLFragmentForNonEmptyString($cellValue);
         } else if (CellHelper::isBoolean($cellValue)) {
             $cellXML .= ' t="b"><v>' . intval($cellValue) . '</v></c>';