Description. Return the number of leading zeros in an integer.

Class. Elemental function.

Argument. `I` must be of type integer.

Result Type and Type Parameter. Same as `I`.

Result Value.
The result is a count of the number of leading 0-bits in the integer `I`.
The model for the interpretation of an integer as a sequence of bits is in
Section 13.5.7 of the Fortran 90 Standard.
`LEADZ(0)` is `BIT_SIZE(I)`.
For nonzero `I`, if the leftmost one bit of `I` occurs in position (where
the rightmost bit is bit 0) then `LEADZ(I)` is `BIT_SIZE(I)` - k.

Examples. `LEADZ(3)` has the value `BIT_SIZE(3) - 2`.
For scalar `I`,
`LEADZ(I) .EQ. MINVAL( (/ (J, J=0, BIT_SIZE(I) ) /), MASK=M )` where
`M =(/ (BTEST(I,J), J=BIT_SIZE(I)-1, 0, -1), .TRUE. /).`
A given integer `I` may produce different results from
`LEADZ(I)`, depending on the number of bits in the representation of the
integer (`BIT_SIZE(I)`).
That is because `LEADZ` counts bits from the most significant bit.
Compare with `ILEN`.

Thu Dec 8 16:17:11 CST 1994