code: public static double cs_norm(DZcs A)
  	{
  		int p, j, n, Ap[] ;
  		DZcsa Ax = new DZcsa() ;
  		double norm = 0, s ;
  		if (!CS_CSC (A) || A.x == null) return (-1) ;	/* check inputs */
  		n = A.n ; Ap = A.p ; Ax.x = A.x ;
  		for (j = 0 ; j < n ; j++)
  		{
  			for (s = 0, p = Ap [j] ; p < Ap [j+1] ; p++) s += cs_cabs(Ax.get(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