code: public static double cs_norm(Dcs A) {
          int p, j, n, Ap[];
          double Ax[], norm = 0, s;
          if (!Dcs_util.CS_CSC(A) || A.x == null)
              return (-1); /* check inputs */
          n = A.n;
          Ap = A.p;
          Ax = A.x;
          for (j = 0; j < n; j++) {
              for (s = 0, p = Ap[j]; p < Ap[j + 1]; p++)
                  s += Math.abs(Ax[p]);
              norm = Math.max(norm, s);
          }
          return (norm);
      }
docs: Computes the 1-norm of a sparse matrix = max (sum (abs (A))), largest
  column sum.
  
  @param A
  column-compressed matrix
  @return the 1-norm if successful, -1 on error