
ln(+Number, -Result)
-Result is ln(+Number)

   Evaluates the natural logarithm ln(Number) and unifies the resulting value
with Result.



Arguments
   Number              A number.
   Result              Output: float or breal.

Type
   Arithmetic

Description

   Evaluates the natural logarithm ln(Number) and unifies the resulting value
   with Result.

   This predicate can be used as a function in arithmetic expressions.
   In coroutining mode, if Number is uninstantiated, the call to ln/2 is
   delayed until this variable is instantiated.




Modes and Determinism
   ln(+, -) is det

Exceptions
     4 --- Number is not instantiated (non-coroutining mode only).
    24 --- Number is not of a numeric type.
    20 --- Illegal arithmetic operation:  Number is 0 or less.

Examples
   
Success:
    Result is ln(2.0).          % gives Result = 0.693147
    Result is ln(1).            % gives Result = 0.0

Error:
    Result is ln(-2).           % arithmetic exception
    Result is ln(0).            % arithmetic exception


See Also
   is / 2
