IsPowerOfTwo {wavethresh}

Decides whether vector elements are integral powers of two (returns NA if not).

Description

This function checks to see whether its input is a power of two. If it is then it returns that power otherwise it returns NA.

Usage

IsPowerOfTwo(n)

Arguments

n

Vector of numbers that are to be checked whether it is a power of two.

Details

Function takes the log of the input, divides this by log(2) and if the result is integral then it knows the input is true power of two.

Value

If n is a power of two, then the power is returned otherwise NA is returned.

RELEASE

Version 3.6.0 Copyright Guy Nason 1995

Author(s)

G P Nason

See Also

nlevelsWT.default.

Examples

#
# Try and see whether 1,2,3 or 4 are powers of two! 
#
IsPowerOfTwo(1:4)
# [1]  0  1 NA  2
#
# Yes, 1,2 and 4 are the 0, 1 and 2nd power of 2. However, 3 is not an
# integral power of two.