/* Return zero if stored volume is zero */
if (Scientific::equals([VFL:m3], 0)) return 0.0;
/* Return unit height if stored volume equals unit volume */
if (Scientific::equals([VFL:m3], [V:m3])) return [DC:m];
/* Solve by Newton's rule */
$x = [DC:m]/2;
while (TRUE) {
  $y = M_PI/3*pow([D:m]*$x/[DC:m], 2)*(3/2*[DC:m]-$x)-[VFL:m3];
  if (Scientific::equals($y, 0)) return $x;
  $x = $x-$y/(M_PI*[D:m]*[D:m]/[DC:m]*$x*(1-$x/[DC:m]));
}

Calculates fill height by using Newton's method of successive approximations (Newton's rule).