code: public void setRow(int i, Vector row) {
          if (columns != row.length()) {
              fail("Wrong vector length: " + row.length() + ". Should be: " + columns + ".");
          }
  
          for (int j = 0; j < row.length(); j++) {
              set(i, j, row.get(j));
          }
      }
docs: Copies given {@code row} into the specified row of this matrix.
  
  @param i the row index
  @param row the row represented as vector