`fplog2``x`procedure- x
- flonum

Computes the base-2 log of

`x`more accurately than`(/ (fplog x) (fplog 2.0))`. In particular,`(fplog2 x)`is correct for any power of two`x`.Examples:

> (fplog2 4.5) 2.169925001442312 > (/ (fplog (fpexp2 -1066.0)) (fplog 2.0)) -1066.0000000000002 > (fplog2 (fpexp2 -1066.0)) -1066.0

Maximum observed error is 0.5006 ulps (see

`fpulp`), but is almost always no more than 0.5 (i.e. it is almost always correct).