fix lattice

src/matrix.rs

@@ -34,7 +34,7 @@ impl Matrix {
 
         // -x0 on diagonal, 0 everywhere else
         let x0 = &ciphertexts[0];
-        for i in 0..n - 1 {
+        for i in 1..n {
             let mut row = vec![int!(0); n];
             row[i] = -x0.clone();
             values.extend(row);
@@ -92,12 +92,12 @@ mod tests {
             int!(4),
             int!(8),
             int!(12),
+            int!(0),
             int!(-5),
             int!(0),
             int!(0),
             int!(0),
             int!(-5),
-            int!(0),
         ];
 
         let lattice = Matrix::new_lattice(noise_bits, ciphertexts).unwrap();