CADability is a pure .net class library for modeling and analyzing 3d data, both with your code and interactively. It comes with an optional Windows.Forms user interface, which can be adopted to other environments. It does not refer to other 3d modeling libraries. For data exchange you can use STEP, STL or DXF files.
If the value of the sweepParameter is (almost) equal to 2.0 * Math.PI this function could return true even tough this is not an Arc but a closed circle.
In a lot of the other functions Precision.eps is used to allow some tolerance.
https://github.com/SOFAgh/CADability/blob/2a5854286b5bb81e64e4a2be374e9e377855d751/CADability/Ellipse.cs#L1726-L1734
If the value of the sweepParameter is (almost) equal to 2.0 * Math.PI this function could return true even tough this is not an Arc but a closed circle. In a lot of the other functions Precision.eps is used to allow some tolerance.