Nth Root of (x) Iteration Process

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    function bcNth_Root_of_X ($N, $x, $Decimals)
{
   $Q = trim($Decimals); // Returned decimals
   $x = trim($x);

   $a = sprintf('%1.16f', pow($x, 1/$N)); // 1st approximation
   $n = $N - 1;
   $D = $Q + 8; // Internal working decimals.

   for ($i=1;  $i <= 50;  $i++)
  {
   $b = bcDiv(bcAdd(bcMul($n,$a,$D),
        bcDiv($x,bcpow($a,$n,$D),$D),$D),$N,$D);

   if (bcComp($a,$b,$D) == 0) {break;} else {$a = $b;}
  }
   return RTrim(RTrim(bcAdd($b, '0.'.Str_Repeat(0,$Q).'5',$Q), '0'),'.');
}