precision issues

[dingtao-shen]

Hi!

I got some problems on the precision issues while using it. When I create a 2D NURBS curve, I found that the precision of the NURBS expression is limited to the single precision. For example, if I create a unit circle with radius of 1.000000000000 the starting points may be shown as (1.000000002311, 0), even though I use the datatype. I wonder if it's an internal limitation, or I didn't use it correctly.

Thanks!