Nested loops with different and dependant steps

This might help you some. (Not exactly what you wanted but it is a start)

j = 0
h = 50
while j <= h:
    n = h/2 - j
    if -3 <= n <= 3:
        i = j
        while i < j + 10:
            n = h/2 - i
            if n <= 0:
                j = h + 70
                print(n)
                break
            i += 0.1
    j += 3

or you could do it like this.

j = 0
h = 50
while j <= h:
  n = h/2 - j
  if -3 <= n <= 3:
    break
  j += 3

i = j
while i < j + 10:
  n = h/2 - i
  if n <= 0:
      print(n)
      break
  i += 0.1