Error assembling diagonal edge-edge matrix

[fredrikbk]

The following fails for @Lugatod:

func foo(q : Quad, p : (Point*4)) -> A : matrix[quads,quads](float)
end

A = map foo to quads reduce +';

[Lugatod]

It will be an easy way to make Identity matrices :

func eye(q:Quad)->I:matrix[quads,quads](float)
    I(q,q)=1.0;
end
I = map eye to quads reduce +;