While support for existing, perpetual licenses may be extended for some customers for a few years, the product is effectively a "legacy" version with no further development or official new sales. This means the only "official" way to have gotten Mathcad 15 was through a valid license purchased before the discontinuation date. Today,
Open the Windows and click on Programs and Features . Select Turn Windows features on or off from the sidebar.
I can provide specific instructions on compatibility settings or guide you through the worksheet migration process. Share public link
If your Mathcad usage focused on heavy matrix manipulations, differential equation solving, and complex data plotting rather than visual documentation, GNU Octave is a premier open-source option. It uses a syntax largely compatible with MATLAB, offering immense computing power without licensing costs. 3. Jupyter Notebooks with Python