Pythagorean theory

I saw pics of this sweater/shawl and found that the pattern was by Twisted Sisters. However they have several books out and can anyone tell me which book this is in?

The Pythagorean jacket is [I]Double Trouble[/I]. It’s all garter stitch so I decreased the sleeve length.

I don’t know about the pythagorean shawl pattern - it’s not in [I]Double Trouble[/I].

HTH
Carolyn