{[= d:double h x n1 n2 (d = 0.0)]
  d: double (1.0 <= d <= 800.0) h:double (100.0 <= h <= 10000.0) 
  x:double (0.0 <= x <= 10000) 
  n1:double (1.0 < n1 <= 2.5) n2:double (1.0 <= n2 <= n1);
}