Error using the 'precision' option - Unrecognized function or variable 'vin': Error in vtkwrite (line 75)

Hello,

This is Matlab R2020b and I'm running into the following issue when trying to change the precision of the VTK output. 

```
>> vtkwrite('mesh.vtk','polydata','triangle',x,y,z,userdata.surface.triRep.Triangulation, 'precision', 5)
Unrecognized function or variable 'vin'.

Error in vtkwrite (line 75)
    precision = num2str(varargin{find(strcmpi(vin, 'PRECISION'))+1});
```