How to fix class autoloading in PHPExcel?

Question

PHP

I include the file classes/PHPExcel.php,
create a new instance of the PHPExcel class and get the error:
PHP Fatal error: Class 'PHPExcel_Calculation' not found
Obviously, the autoloader is weird. Perhaps this is due to the fact that spl autoloader does not work well with CamelCase, but no solution to this problem was found on Google. PHP Version - 5.3.10

Answer 1

It is customary to include libraries in PHP using composer.
This will solve the problem.
And PHP should be updated.

Answer 2

Specify the absolute path to the class