[ Arithmetic | Reference Manual | Alphabetic Index ]

abs(+Number, -Result)

Unifies the absolute value of Number with Result.
Number
A number.
Result
A variable or a number.

Description

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

Number and Result have to be of the same type.

In coroutining mode, if Number is uninstantiated, the call to abs/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.

Examples

Success:
      abs(1, 1).
      abs(-5, Result).             (gives Result = 5)
      abs(-6.2, Result).           (gives Result = 6.2)
Fail:
      abs(1, 0).
      abs(1, 1.0).
      abs(-1.0, 1).
      abs(1, r).
Error:
      abs(A, 6).                   (Error 4).
      abs(4 + 2, 6).               (Error 24).



See Also

is / 2