matrix multiplication

<?php
//----------------------------
//-- matrix multiplication
//-- 120925 cahyadsn@yahoo.com
//-----------------------------
$a = array(array(2,1),array(4,5),array(6,7));
print_matrix($a,$title='MATRIK A');
$b = array(array(2,3,2),array(1,1,-3));
print_matrix($b,$title='MATRIK B');
if(count($a[0])==count($b)){
  for($i=0;$i<count($a);$i++){
    for($j=0;$j<count($b[0]);$j++){
      $c[$i][$j]=0;
      for($k=0;$k<count($b);$k++){
        $c[$i][$j]+=$a[$i][$k]*$b[$k][$j];
      }
    }
  }
  print_matrix($c,$title='MATRIK C (AB)');
}else{
  echo "jumlah kolom matrik pertama != jumlah baris matrik kedua";
}

function print_matrix($mat,$title=''){
  echo "<pre>$title=\n";
  for($i=0;$i<count($mat);$i++){
    for($j=0;$j<count($mat[0]);$j++){
      echo str_pad($mat[$i][$j],5,' ',STR_PAD_BOTH);
    }
    echo "\n";
  }
  echo "</pre>";
}
?>