How to tell if a number is a "POWER of 2"-number
SELECT Number,
1 - SIGN(Number & (Number - 1))
FROM master..spt_values
WHERE Type = 'P'
AND Number > 0
Other way is
CREATE FUNCTION dbo.isPowerOf2
(
@i INT
)
RETURNS BIT
AS
BEGIN
DECLARE @x FLOAT
SET @x = LOG(Number) / LOG(2)
RETURN CASE
WHEN FLOOR(@x) = CEILING(@x) THEN 1
ELSE 0
END
END
(
@i INT
)
RETURNS BIT
AS
BEGIN
DECLARE @x FLOAT
SET @x = LOG(Number) / LOG(2)
RETURN CASE
WHEN FLOOR(@x) = CEILING(@x) THEN 1
ELSE 0
END
END
Legacy Comments
|
RamiReddy
2008-08-13 |
re: How to tell if a number is a "POWER of 2"-number Is that first query will work for the number 524288 which is 2 power 19. it will not work for that number. that query has a limitation. it will work only for the values which are in that table. table records are finite. but 2 power numbers are infinite. |