Smooth Mesh to Surface

Hi,

I found this scrip from:

http://www.grasshopper3d.com/forum/topics/convert-lowpoly-mesh-to-s...

by  Vicente Soler

but the thing is that it doesn't work for three sided meshes and it comes up with 

"1. Index was outside the bounds of the array. (line: 0)"

and I  don't know C script

essentially im trying to make sail like forms from triangular meshes so it needs to be smooth and able to be rebuilt so i can slightly touch it up.

Could someone please help me edit the script so it works with three sided meshes

Thank you so much in advance!!!!