void solve(ZZ_pE& d, vec_ZZ_pE& X, 
           const mat_ZZ_pE& A, const vec_ZZ_pE& b)

{
   long n = A.NumRows();
   if (A.NumCols() != n)
      Error("solve: nonsquare matrix");

   if (b.length() != n)
      Error("solve: dimension mismatch");

   if (n == 0) {
      set(d);
      X.SetLength(0);
      return;
   }

   long i, j, k, pos;
   ZZ_pX t1, t2;
   ZZ_pX *x, *y;

   const ZZ_pXModulus& p = ZZ_pE::modulus();

   vec_ZZ_pX *M = NTL_NEW_OP vec_ZZ_pX[n];

   for (i = 0; i < n; i++) {
      M[i].SetLength(n+1);
      for (j = 0; j < n; j++) {
         M[i][j].rep.SetMaxLength(2*deg(p)-1);
         M[i][j] = rep(A[j][i]);
      }
      M[i][n].rep.SetMaxLength(2*deg(p)-1);
      M[i][n] = rep(b[i]);
   }

   ZZ_pX det;
   set(det);

   for (k = 0; k < n; k++) {
      pos = -1;
      for (i = k; i < n; i++) {
         rem(t1, M[i][k], p);
         M[i][k] = t1;
         if (pos == -1 && !IsZero(t1)) {
            pos = i;
         }
      }

      if (pos != -1) {
         if (k != pos) {
            swap(M[pos], M[k]);
            negate(det, det);
         }

         MulMod(det, det, M[k][k], p);

         // make M[k, k] == -1 mod p, and make row k reduced

         InvMod(t1, M[k][k], p);
         negate(t1, t1);
         for (j = k+1; j <= n; j++) {
            rem(t2, M[k][j], p);
            MulMod(M[k][j], t2, t1, p);
         }

         for (i = k+1; i < n; i++) {
            // M[i] = M[i] + M[k]*M[i,k]

            t1 = M[i][k];   // this is already reduced

            x = M[i].elts() + (k+1);
            y = M[k].elts() + (k+1);

            for (j = k+1; j <= n; j++, x++, y++) {
               // *x = *x + (*y)*t1

               mul(t2, *y, t1);
               add(*x, *x, t2);
            }
         }
      }
      else {
         clear(d);
         goto done;
      }
   }

   X.SetLength(n);
   for (i = n-1; i >= 0; i--) {
      clear(t1);
      for (j = i+1; j < n; j++) {
         mul(t2, rep(X[j]), M[i][j]);
         add(t1, t1, t2);
      }
      sub(t1, t1, M[i][n]);
      conv(X[i], t1);
   }

   conv(d, det);

//.........这里部分代码省略.........