Description. Returns one less than the length, in bits, of the
two's-complement representation of an
integer.
Class. Elemental function.
Argument. I must be of type integer.
Result Type and Type Parameter. Same as I.
Result Value.
If I is nonnegative, ILEN(I) has the value ;
if I is negative, ILEN(I) has the value
.
Examples.
ILEN(4) = 3. ILEN(-4) = 2.
2**ILEN(N-1) rounds N up to a power of 2 (for ), whereas 2**(ILEN(N)-1) rounds N down to a power of
2. Compare with LEADZ.
The value returned is one less than the length of the
two's-complement representation of I, as the following explains.
The shortest two's-complement representation of is
. The
leading zero is the required sign bit. In 3-bit two's complement,
represents
.