[ Arithmetic | The ECLiPSe Built-In Predicates | 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

- abs(+, -) is det

### Exceptions

(4) instantiation fault
  Number is not instantiated (non-coroutining mode only).
(5) type error
  Result and Number are numbers of different types.
(24) number expected
  Number is not of a numeric type.
(24) number expected
  Result is neither a number nor a variable.

## Examples

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

## See Also

is / 2