This document outlines the differences between version 3.5a and version 4.0a. It also outlines additions that we plan to make in COMSOL Multiphysics version 4.1.
We have strived to achieve backward compatibility with the previous version and to include all functionality that is available there. COMSOL 4.0a is compatible with COMSOL 3.5a and COMSOL 4.0 with some exceptions. Those exceptions are noted in this document.
In the menu to the right you will find release notes for each product.