The TINV formula result is different from MS Excel / LibreOffice when the degrees of freedom is 1

[fauzie811]

This is:

• a bug report
• a feature request
• not a usage question (ask them on https://stackoverflow.com/questions/tagged/phpspreadsheet or https://gitter.im/PHPOffice/PhpSpreadsheet)

What is the expected behavior?

It should returns: 12.7062047

What is the current behavior?

It returns: 1.8373862310371

What are the steps to reproduce?

Please provide a Minimal, Complete, and Verifiable example of code that exhibits the issue without relying on an external Excel file or a web server:

<?php

require __DIR__ . '/vendor/autoload.php';

$calculation = \PhpOffice\PhpSpreadsheet\Calculation\Calculation::getInstance();

$formula = '=TINV(0.05, 1)';
$result = $calculation->_calculateFormulaValue($formula);

What features do you think are causing the issue

• Reader
• Writer
• Styles
• Data Validations
• Formula Calculations
• Charts
• AutoFilter
• Form Elements

Does an issue affect all spreadsheet file formats? If not, which formats are affected?

Not sure.

Which versions of PhpSpreadsheet and PHP are affected?

2.2