NAME
    ilog2 - floor of logarithm to base 2

SYNOPSIS
    ilog2(x)

TYPES
    x		nonzero real

    return	integer

DESCRIPTION
    Returns the greatest integer n for which 2^n <= abs(x).

EXAMPLE
    > print ilog2(1), ilog2(2), ilog2(3), ilog2(4), ilog(1/15)
    0 1 1 2 -4

LIMITS
    none

LIBRARY
    long qilog2(NUMBER *q)

SEE ALSO
    ilog10, ilog