Returns the tick ration of the length-symbol. Converting length symbols first to ratios allows to use the results in calculations without losing the absolute resolution achieved by the autocorrection (see get-tick).
(get-ratio '1/2)
--> 1/2
(get-ratio '-1/2..)
--> -7/8
The ratio returned by get-ratio can be processed with get-tick, and it is autocorrected to the tick resolution.
(get-ratio '1/2...)
--> 15/16
(get-tick '1/2...)
--> 1800
(get-tick (get-ratio '1/2...))
--> 1800
Note that the type is by default :symbol. This means that when get-ratio expands 1/1, 2/1 etc, it returns them as symbols. If :integer is used then the output will be integers 1, 2 etc.