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ln(+Number, -Result)

Evaluates the natural logarithm ln(Number) and unifies the resulting value with Result.
Number
A number.
Result
A variable float or breal.

Description

This predicate is used by the ECLiPSe compiler to expand evaluable arithmetic expressions. So the call to ln(Number, Result) is equivalent to
    Result is ln(Number)
which should be preferred for portability.

In coroutining mode, if Number is uninstantiated, the call to ln/2 is delayed until this variable is instantiated.

Modes and Determinism

Exceptions

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

Examples

Success:
      ln(2.0, Result).          (gives Result = 0.693147)
      ln(1, Result).            (gives Result = 0.0)
Fail:
      ln(1, 1.0).
      ln(1, 0).
      ln(1, r).
Error:
      ln(A, 6.0).                   (Error 4).
      ln(-2, Result).               (Error 20).
      ln(0, Result).                (Error 20).
      ln(4 + 2, 1.79176).           (Error 24).



See Also

is / 2