[ 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 a free variable, the call to abs/2 is
delayed until this variable is instantiated.
Fail Conditions
Fails if the result of the evaluation does not unify with Result.
Resatisfiable
No
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