lib/BN.php
public function isubn($num) {
        assert(is_numeric($num));
        $this->bi = $this->bi->sub(intval($num));
        return $this;
    }
public function isubn($num) {
        assert(is_numeric($num));
        $this->bi = $this->bi->sub(intval($num));
        return $this;
    }
public function isubn ( $ num ) { assert ( is_numeric ( $ num ) ) ; $ this -> bi = $ this -> bi -> sub ( intval ( $ num ) ) ; return $ this ; }
Subtract plain number `num` from `this`
Subtract plain number num from this