The speeds and rules of warp have been changed so many times just make up your own.
Depending upon the episode... may or may not be polynomial, exponential, even when there is a formula it isn't followed, warp 10 may or may not be the speed limit (in an TOS episode they went at warp 14 i think).
Depending upon the episode... may or may not be polynomial, exponential, even when there is a formula it isn't followed, warp 10 may or may not be the speed limit (in an TOS episode they went at warp 14 i think).