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>>(+Number1, +Number2, ?Result)

Shifts Number1 right arithmetically by Number2 bits and unifies the resulting value with Result.
+Number1
Integer.
+Number2
Integer.
?Result
A variable or integer.

Description

This predicate is used by the ECLiPSe compiler to expand evaluable arithmetic expressions. So the call to >>(Number1, Number2, Result) is equivalent to 
    Result is Number1 >> Number2
which should be preferred for portability. The effect of negative shift counts and shift counts greater than 31 is machine dependent.

In coroutining mode, if Number1 or Number2 are free variables, the call to >>/3 is delayed until these variables are instantiated.

Fail Conditions

Fails if the result of the evaluation does not unify with Result.

Resatisfiable

No

Exceptions

(4) instantiation fault
Number1 or Number2 is not instantiated (non-coroutining mode only).
(5) type error
Result is a number but not an integer.
(5) type error
Number1 or Number2 is a number but not an integer.
(24) number expected
Number1 or Number2 is not of a numeric type.
(24) number expected
Result is neither a number nor a variable.

Examples

Success:
      >>(8, 3, 1).
      >>(17, 3, X).          (gives X = 2)
Fail:
      >>(1, 2, 3).
Error:
      >>(A, 2, 6).              (Error 4).
      >>(16, 2.0, 4.0).         (Error 5).
      >>(4 + 12, 2, 4).         (Error 24).
      >>(5, 2, r).              (Error 24).

See Also

is / 2