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Has anyone an idea, why calculating a product from small numbers in the new Mathematica 12.1 does not give the same results as Mathematica 11.2? For the complete example, which is a part of a likelihood computation, see the attached notebook. ...
You also can use: EXTERN_C DLLEXPORT int CreateMatrix(WolframLibraryData libData, mint Argc, MArgument *Args, MArgument Res)