[ Arithmetic | Reference Manual | Alphabetic Index ]

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

-Result is +Number1 >> +Number2

Shifts Number1 right arithmetically by Number2 bits and unifies the resulting value with Result.
Number1
Integer.
Number2
Integer.
Result
Output: integer.

Description

Shifts Number1 right arithmetically by Number2 bits and unifies the resulting value with Result.

The shift behaves as an arithmetic (signed) shift operating on an unlimited length two's complement representation. Shifting by a negative amount is the same as shifting by the same positive amount in the other direction.

This predicate can be used as a function in arithmetic expressions. In coroutining mode, if Number1 or Number2 are uninstantiated, the call to >>/3 is delayed until these variables are instantiated.

Modes and Determinism

Exceptions

(4) instantiation fault
Number1 or Number2 is not instantiated (non-coroutining mode only).
(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.

Examples

Success:
    Result is 8 >> 3.		% gives Result = 1
    Result is 17 >> 3.		% gives Result = 2
    Result is 10 >> 1.		% gives Result = 5

    Result is 5 >> -1.		% gives Result = 10

    Result is -10 >> 1.		% gives Result = -5

Error:
    Result is 1.1 >> 3.		% type error

See Also

is / 2