Need someone to test a function for me

/*
* function create_index( string|array $tbl_name [, string|array $idx_name [, boolean $silent]])
*   @string /or\ array $tbl_name - The table name(s) to create the index on
*   @string /or\ array $idx_name - The index name for the table names
*   @boolean $silent - If set to true, the errors would be silenced and would
*     be stored into the error variable.
*
* Creates an index for table name(s) put into the script with the index name
* either generated automatically (if none provided) or using the ones provided.
*/

function create_index($tbl_name, $idx_name = null, $silent = false)
{
  // Checking if we are allowed to create an index
  if($this->all_funcs['CREATE_INDEX'] != 1)
  {
    trigger_error("Current MySQL user could not create index on $tbl_name. ", E_USER_ERROR);
  }
  
  // Initiating the IDX array
  $idx = array();
  
  // Checking if submitted information are of correct datatype
  if(is_array($tbl_name) && is_null($idx_name) || !is_array($idx_name))
  {
    // Iterating through the $tbl_name array and adding the name to the array
    foreach($tbl_name as $value)
    {
      $idx[$value] = 'IDX_' . $value;
    }
  }
  
  // Checking if both variables are arrays
  if(is_array($idx_name) && is_array($tbl_name) && !is_null($idx_name))
  {
    // Counting number of values in $tbl_name and $idx_name
    $tbls = count($tbl_name);
    $idxs = count($idx_name);
    
    // Checking if $tbls equal $idxs
    if($tbls == $idxs)
    {
      // Creating the IDX array holding the information
      for($i = 0; $i<=$tbls; ++$i)
      {
        $idx[$tbl_name[$i]] = $idx_name[$i];
      }
    }
    else
    {
      return false;
    }
  }
  
  // Checking if it's only one table to create index on
  if(!is_array($tbl_name) && !is_array($idx_name))
  {
    // Creating the IDX array for it.
    $idx[$tbl_name] = $idx_name;
  }
  
  // Checking if $idx_name is of illegal type
  if(!is_array($idx_name) || !is_null($idx_name) && is_array($tbl_name))
  {
    // Checking if the errors were silenced
    if($silent)
    {
      $this->error = 'The variable <strong>$idx_name</strong> is of illegal datatype in <strong>' . __FILE__ . '</strong> on line <strong>' . __LINE__ . '</strong>.';
    }
    else
    {
      trigger_error('The variable <strong>$idx_name</strong> is of illegal datatype ', E_USER_ERROR);
    }
    return false;
  }
  
  // Initiating the SQL array
  $sql = array();
  
  // Filling the SQL array with SQL query data
  foreach($idx as $tbl => $idx)
  {
    $sql[] = "CREATE INDEX {$idx} ON {$tbl}";
  }
  
  // Carrying out the action
  foreach($sql as $query)
  {
    // Carrying out the SQL queries and making sure that they are not false
    if(!$this->set_result_resource($query, true))
    {
      $return = false;
      break;
    }
  }
  
  // Checking if there were any errors in the script
  if($return === false)
  {
    
    // Checking if the errors were silenced
    if($silent)
    {
      $this->error = mysql_error() . ' in <strong>' . __FILE__ . '</strong> on line <strong>' . __LINE__ . '</strong>.';
    }
    else
    {
      // Echoing out the MySQL Error
      trigger_error(mysql_error(), E_USER_ERROR);
    }
  }
  
  // Returning true if there were no errors
  if($return != false)
  {
    return true;
  }
}