I want to issue the stellar equivalent of ethereum. Ethereum requires at least 18 units of precision but the amount on stellar is capped at int64 max. This isnt restricted to Ethereum so my question is how to issue an asset of an arbitary precision?
To my knowledge you can't do this. Asset amounts are scaled down to seven decimal places for human readability.
The smallest non-zero amount unit is 0.0000001 (one ten-millionth) represented as an integer value of one. The largest amount unit possible is ((2^63)-1)/(10^7) (derived from max int64 scaled down) which is 922,337,203,685.4775807.
Ethereum chooses to handle precision differently.