     }
 
     func cascadeZeros() {
-        let E = self
         let N = maxDegree
         if N == 2 {
             return

    func cotarget(_ p: Int, _ q: Int) -> (Int, Int) {
        let r = degree
        return (p - r, q + r - 1)
    }
    
    var detailDescription : String {

        
        for (p, q, g) in self[2] {
            if g.isZero {
                for r in (3 ... N) {
                    let Er = self[r]
                    Er[p, q] = 0
                }
            }
        }
