Mesh.Vertices accuracy seems wrong, why?

[djordje]

It is not a mistake.
Rhino records mesh vertices as a single point precision numbers:

"Mesh split plane" component fails

Thank you for all the testing and replies both @laurent_delrieu and @diff-arch! Rhino mesh vertex coordinates are defined by single precision floating point numbers: https://developer.rhino3d.com/api/RhinoCommon/html/T_Rhino_Geometry_Point3f.htm A rule of thumb is that for single floating point numbers, there are approximatelly 7 digits precision. Plenty of webpages online can be found, showing how to precisely calculate it for a specific number (range): For a given 85395.52 document uni…

So the second value that you see is probably conversion of the single point precision to double (called “float” in python).

As pirate suggested you should always use tolerance when comparing two numbers.