php - Undefined Offset while looping -

i have problem in code, when im trying give value array variable location. code working, there many notification said "undefined offset " looping when im tryng loop variable.`

                  $query_jur="select * t_jurusan order id_jurusan";                   $sql_jur=mysql_query($query_jur);                   if (mysql_num_rows($sql_jur)==0) {                   echo "kosong";                   $jml_jur=mysql_num_rows($sql_jur);                   } else {                   $jml_jur=mysql_num_rows($sql_jur);                   echo "jumlah jurusan yang diinputkan pada tabel jurusan adalah : ",$jml_jur;                   echo "<br>";                   }                   $query_ins="select * t_ins_akreditasi_jur order id_kriteria";                   $sql_ins=mysql_query($query_ins);                   if (mysql_num_rows($sql_ins)==0) {                   $jml_ins=mysql_num_rows($sql_ins);                   echo "kosong";                   } else {                   $jml_ins=mysql_num_rows($sql_ins);                   echo "jumlah instrumen yang diinputkan pada tabel instrumen adalah : ",$jml_ins;                   }                    $query_select_hasil="select t_hasil_ins.id_jurusan, t_hasil_ins.id_kriteria, t_ins_akreditasi_jur.id_sub, t_hasil_ins.nilai, t_hasil_ins.hasil, t_hasil_ins.ket t_hasil_ins, t_ins_akreditasi_jur t_ins_akreditasi_jur.id_kriteria=t_hasil_ins.id_kriteria order id_kriteria";                   $sql_hasil=mysql_query($query_select_hasil);                   $data_hasil=mysql_fetch_array($sql_hasil);                   echo $data_hasil['id_sub'];                        $query_jurusan="select * t_jurusan order id_jurusan";                      $sql_jurusan=mysql_query($query_jurusan);                     $i=1;                       $index_jur=array();                     $index_sub=array();                     $index_jur_sub=array();                     $index_bobot=array();                     $index_nilai=array();                     $nilai_sementara=array();                     $index_nilai_akhir_sub=array();                     $index_nilai_akhir_jur=array();                     $sql_del1 = mysql_query("delete t_hasil_rank_instrumen_standar ") or die(mysql_error());                     while ($data_jurusan=mysql_fetch_array($sql_jurusan)){                         $index_jur[$i]=$data_jurusan['id_jurusan'];                         echo "<br>";                         echo "id jurusan : ",$index_jur[$i];                         $query_sub="select * t_sub_kriteria order id_sub";                         $sql_sub=mysql_query($query_sub);                         $j=1;                         while ($data_sub=mysql_fetch_array($sql_sub)){                             $index_sub[$j]=$data_sub['id_sub'];                             echo "-->";                             echo "id sub : ",$index_sub[$j];                             $query_jur_sub="select t_hasil_ins.id_jurusan, t_hasil_ins.id_kriteria, t_ins_akreditasi_jur.id_sub, t_hasil_ins.nilai, t_hasil_ins.hasil, t_hasil_ins.ket t_hasil_ins, t_ins_akreditasi_jur t_ins_akreditasi_jur.id_kriteria=t_hasil_ins.id_kriteria , t_hasil_ins.id_jurusan='$index_jur[$i]' , id_sub='$index_sub[$j]' order id_kriteria";                             $sql_jur_sub=mysql_query($query_jur_sub);                             $k=1;                                $index_nilai_akhir_sub[$i][$j]=0;                             while ($data_jur_sub=mysql_fetch_array($sql_jur_sub)){                                 $index_jur_sub[$k]=$data_jur_sub['id_kriteria'];                                 $index_nilai[$k]=$data_jur_sub['nilai'];                                 $keterangan[$k]=$data_jur_sub['ket'];                                 echo "<br>";                                 echo " ( ",$index_jur_sub[$k]," ) ";                                     $query_bobot="select * t_ins_akreditasi_jur id_kriteria='$index_jur_sub[$k]'";                                     $sql_bobot=mysql_query($query_bobot);                                     $data_bobot=mysql_fetch_array($sql_bobot);                                     $index_bobot[$k]=$data_bobot['bobot'];                                     echo "<br>";                                     echo " dengan bobot ",$index_bobot[$k];                                     echo "<br>";                                     echo " dan nilai ",$index_nilai[$k], "tapi, keteranganya ",$keterangan[$k] ;                                     echo "<br>";                                     if ($keterangan[$k]=="0"){                                     $nilai_sementara[$k]=$index_bobot[$k]*0;                                     } else {                                     $nilai_sementara[$k]=$index_bobot[$k]*$index_nilai[$k];                                     }                                      echo "hasil * kali : ",$nilai_sementara[$k];                                     $index_nilai_akhir_sub[$i][$j]=$index_nilai_akhir_sub[$i][$j]+$nilai_sementara[$k];                                 $k++;                                 }                                 echo "<br>";                                 echo "hasil akhir jurusan ",$index_jur[$i]," sub ",$j," : ",$index_nilai_akhir_sub[$i][$j];                                 echo "<br>";                                 if($index_nilai_akhir_jur[$i]==0){                                 $index_nilai_akhir_jur[$i]=$index_nilai_akhir_sub[$i][$j];                                 } else {                                 $index_nilai_akhir_jur[$i]=$index_nilai_akhir_jur[$i]+$index_nilai_akhir_sub[$i][$j]; error happen here :(                                 }                               $j++;                             }                             echo "hasil akhir jurusan ",$index_jur[$i]," tanpa sub adalah  : ",$index_nilai_akhir_jur[$i];                             echo "<br>";                             $sql_insert1 = mysql_query("insert t_hasil_rank_instrumen_standar values ('$index_jur[$i]','$index_nilai_akhir_jur[$i]','','')");                       $i++;                      }                ?>`  

this happens when try use , array variable no value, try this:

if (isset($index_nilai_akhir_jur[$i]) && isset($index_nilai_akhir_sub[$i][$j])){ $index_nilai_akhir_jur[$i]=$index_nilai_akhir_jur[$i]+$index_nilai_akhir_sub[$i][$j];}