code: public static boolean isVector(DMatrixSparseCSC a) {
          return (a.numCols == 1 && a.numRows > 1) || (a.numRows == 1 && a.numCols>1);
      }
docs: Returns true if the input is a vector
  @param a A matrix or vector
  @return true if it's a vector.  Column or row.