# Create a ring of successive doubles

``

    doubles  start (number), num_doubles (int)

Create a ring containing the results of successive doubling of the `start` value. If `num_doubles` is negative, will return a ring of `halves`.

Introduced in v2.10

## Examples

# Example 1
``
    (doubles 60, 2)
| ``
    #=> (ring 60, 120)
# Example 2
``
    (doubles 1.5, 3)
| ``
    #=> (ring 1.5, 3, 6)
# Example 3
``
    (doubles 1.5, 5)
| ``
    #=> (ring 1.5, 3, 6, 12, 24)
# Example 4
``
    (doubles 100, -4)
| ``
    #=> (ring 100, 50, 25, 12.5)