Radius of a 3DCurve: use "curvature" command to get a radius of a curve...

Hello Everyone,
I have another problem ... ^ __ ^!
I do not know how to use the command "curvature" of Grasshopper.

This command returns three vectors but if I measure a curve using the "Radius Analysis", of Rhino3D, I get a radius, and even a circle at the point of the curve measured.
How can I get the same result, and ,above all, a numerical value of radius?

Thank you so much!