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acos(+Number, -Result)

Evaluates the trigonometric function acos(Number) and unifies the resulting value with Result.
A number.
Output: float.


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

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

Modes and Determinism


(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 greater than 1 or less than -1.
(141) unimplemented functionality
Argument is of type breal


    Result is acos(1.0).	% gives Result = 0.0).
    Result is acos(-0.5).	% gives Result = 2.0944
    Result is acos(0).		% gives Result = 1.5708

    Result is acos(2.0).	% arithmetic exception

See Also

is / 2