how to form unit vector generator block?

Hi guys, I'm working with the simulation of closed loop PI Algorithm for the reduction of harmonics. Here I got difficulty in forming unit vector generator block. 

I had searched in matlab help, but none of the search terms lead me for any improvement. Please help me.

Many thanks in advance.

[Rick Rosson]

What product(s) are you using? MATLAB, Simulink, which Toolboxes, which Blocksets?