LN returns the natural log of the argument.
The argument can be a numeric value or any type that can be implicitly converted to a numeric value.
The function returns a value that is the same type as the numeric argument type unliess the argument is a BINARY_FLOAT. In this case the function returns a BINARY_DOUBLE.
Example:
SELECT LN(20) as log_value from dual;
LOG_VALUE
——————-
2.99573227
Ln – Oracle SQL Function