For sale is Mathcad Prime 3.1 SDK which is a package of documentation and source code examples including source to the Solidworks- Mathcad Prime integration.
The installation itself it is free for PTC customers: Download here
The SDK guide pdf is included there in \doc subfolder.
Notes:
Do not mix SDK up with Mathcad Prime API or Custom functions (For example C:\Program Files\PTC\Mathcad Prime 6.0.0.0\Custom Functions)
The API is part of every Mathcad Prime installation, including Ptc.MathcadPrime.Automation.tlb and Ptc.MathcadPrime.Automation.dll
- Example: Load the TLB into the Object Browser of MS Visual Studio (or Visual Studio Express free) and there are the API's, including methods, properties, enumerations and data types
Hope this helps.