hola a todos estoy haciendo un trabajo y veo que todo esta bien no c si tendre error sintactico o semantico haber si me pudieran ayudar a encontrar el error ante todo gracias
NOTA : EL ERROR K ME MANDA ES Notice: Undefined offset: 4 on line 95

<?php
function operacions(){
$w = array();
$n=array();
$s=array();
 
$w[0] = 0;
$w[1] = $_POST['textfield'];
$w[2] = $_POST['textfield2'];
$w[3] = $_POST['textfield3'];
$w[4] = $_POST['textfield4'];
$w[5] = $_POST['textfield5'];
$w[6] = $_POST['textfield6'];
$w[7] = $_POST['textfield7'];
$w[8] = $_POST['textfield8'];
$w[9] = $_POST['textfield9'];
 
$p[0][0] = -1.2235799146141384;
$p[0][1] = -0.70010651874909657;
$p[0][2] = -1.7731918655820678;
$p[0][3] = -1.5251175021147345;
$p[0][4] = -1.4204655443213379;
$p[1][0] = -0.97597916371135185;
$p[1][1] = -0.61944032134122518;
$p[1][2] = -1.3252910059416212;
$p[1][3] = -1.1613073466706523;
$p[1][4] = -1.1000196116669476;
$p[2][0] = -0.26297697272996906;
$p[2][1] = -0.23017656306151368;
$p[2][2] = -0.28660735736717136;
$p[2][3] = -0.30506804246600422;
$p[2][4] = -0.28507216010282443;
$p[3][0] = -0.58127450390378232;
$p[3][1] = -0.40312099212301156;
$p[3][2] = -0.667891032602475;
$p[3][3] = -0.59683006060119459;
$p[3][4] = -0.5576844603158182;
$p[4][0] = -0.88082840385755279;
$p[4][1] = -0.64670843710188453;
$p[4][2] = -1.1407131043566223;
$p[4][3] = -1.0190595034999201;
$p[4][4] = -0.98346546463809648;
$p[5][0] = 0.39415634038838759;
$p[5][1] = 0.21275458581178319;
$p[5][2] = 0.57452929355071458;
$p[5][3] = 0.45308581253591212;
$p[5][4] = 0.4460237495227507;
$p[6][0] = -0.40963368809392037;
$p[6][1] = -0.32399833966230368;
$p[6][2] = -0.45218994859103551;
$p[6][3] = -0.43632639215123181;
$p[6][4] = -0.43120076440125027;
$p[7][0] = -0.5316008907672557;
$p[7][1] = -0.47966253065162245;
$p[7][2] = -0.76002669669074152;
$p[7][3] = -0.65185665139227611;
$p[7][4] = -0.610677578929192;
$p[8][0] = -0.19786829015470639;
$p[8][1] = -0.17679641652232761;
$p[8][2] = -0.1864234465185225;
$p[8][3] = -0.1573874225682983;
$p[8][4] = -0.14823125113185592;
$p[9][0] = -0.36780995956956208;
$p[9][1] = -0.3123170582785918;
$p[9][2] = -0.48843241496346657;
$p[9][3] = -0.39673206878632694;
$p[9][4] = -0.45742531757471755;
$m[0][0] = -3.1574236408363991;
$m[0][1] = 3.1541461024381205;
$m[1][0] = 1.2461274535765703;
$m[1][1] = -1.2724099490193193;
$m[2][0] = 0.62839610446573657;
$m[2][1] = -0.611180041896025;
$m[3][0] = 2.0484161759032462;
$m[3][1] = -2.0648648115959993;
$m[4][0] = 1.6570006755376996;
$m[4][1] = -1.6324609140925035;
$m[5][0] = 1.5278432097144548;
$m[5][1] = -1.5227543035639044;
for($i=0;$i<4;$i++){
   $neta=0;
for($j=0;$j<9;$j++)
{
  $ne = $w[$j] * $p[$j][$i];
  $neta = $neta + $ne;
 
}
$n[$i] = $neta;
}
$n[0] = 1;
for($i=0;$i<1;$i++){
   $neta1=0;
for($j=0;$j<5;$j++)
{
   $ne1 = $n[$j] * $m[$j][$i];
  $neta1 = $neta1 + $ne1;
   if($neta1 > 0)
   {
      $sa=1;
   }
   else
   {
      $sa = 0;
   }  
}
$s[$i] = $sa;
}
if(($s[0] == 0) && ($s[1] == 0))
{
   echo "Si tiene Cancer";
}
else
{
   if(($s[0] == 0) && ($s[1] == 1))
   {
   echo "Si tiene Cancer";
    }
	else
	{
	    if(($s[0] == 1) && ($s[1] == 0))
          {
             echo "No tiene Cancer";
       }
	   else
	   {
	      echo "No tiene Cancer";
	   }
	}
}
}
?>