// Return zero if stored volume is zero
if (Scientific::equals([VST:m3], 0)) return 0.0;
// Return unit height if stored volume equals unit volume
if (Scientific::equals([VST:m3], [V:m3])) return [D:m];
// Solve by Newton's rule
$x = [D:m] / 2;
while (TRUE) {
  $sx = sqrt(([D:m] - $x) * $x);
  $y = [L:m] * ([D:m] * [D:m] / 4 * acos(1 - 2 * $x / [D:m]) - ([D:m] / 2 - $x) * $sx) + M_PI * [DC:m] * $x * $x * (1 / 2 - $x / (3 * [D:m])) - [VST:m3];
  if (Scientific::equals($y, 0)) return $x;
  $x = $x - $y / ($sx * (2 * [L:m] + M_PI * [DC:m] / [D:m] * $sx));
}

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

Volume is only used to check the boundary condition at the beginning.