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

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



Arguments
   Number1             Integer.
   Number2             Integer.
   Result              Output: integer.

Type
   Arithmetic

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 shift behaves as if 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.

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




Modes and Determinism
   <<(+, +, -) is det

Exceptions
     4 --- Number1 or Number2 is not instantiated (non-coroutining mode    only).
     5 --- Number1 or Number2 is a number but not an integer.
    24 --- Number1 or Number2 is not of a numeric type.

Examples
   
Success:
    Result is 1 << 3.		% gives Result = 8
    Result is 5 << 1.		% gives Result = 10

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

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

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


See Also
   is / 2
