function newt_raph($C0)
{
$conv_criterion=1;
$tolerance=pow(10,-8);
$i=1;
while(($i<1000)&&($conv_criterion>$tolerance))
{
# echo "The number is " . $i . "<br />";
$Fx= flooding($C0);
$JFx= jac($C0);
$Cnew=$C0-$Fx/$JFx;
$conv_criterion=abs($Cnew-$C0)/$C0;
$C0=$Cnew;
$i++;
}
return $C0;
}
function jac($C0)
{
$eps = $C0 / 1000;
if ($eps == 0) {
$eps = 1 / 1000;
}
$Cp = $C0;
$Cp = $Cp + $eps;
$Fp = flooding($Cp);
$Cn = $C0;
$Cn = $Cn - $eps;
$Fn = flooding($Cn);
$J = ($Fp - $Fn) / (2 * $eps);
return $J;
}