Hi,
>> I'm mostly using log2 to work out if numbers are a power of two and find
>> the highest bit that they have set.
>>
>> Is there a more robust way to do that in CHICKEN when using the numbers
>> egg and bignums?
>
> It's probably better to do something like this:
>
> (= (arithmetic-shift 1
Andy Bennett scripsit:
> I'm mostly using log2 to work out if numbers are a power of two and find
> the highest bit that they have set.
You can use integer-length to tell how many bits are required. If you
subtract 1 and the number of bits shrinks by 1, you have a power of 2.
Rules for WWI
On Fri, Apr 01, 2016 at 06:23:28PM +0100, Andy Bennett wrote:
> Thanks Peter!
>
> I'm mostly using log2 to work out if numbers are a power of two and find
> the highest bit that they have set.
>
> Is there a more robust way to do that in CHICKEN when using the numbers
> egg and bignums?
It's
Peter Bex scripsit:
> That's a complete mischaracterisation. First, it depends on your
> definition of "accurately", and secondly, you can tell CHICKEN to
> change the print precision. See my other mail, which shows that
> Racket is _also_ truncating the value, just after more digits than
>
Hi,
>> Is it just late on a Friday? Am I crazy?
>
> Floating point numbers are weird enough to drive anyone bat shit:
>
> #;1> (use numbers)
> #;2> (define (log2 n) (/ (log n) (log 2)))
> #;3> (log2 (expt 2 251))
> 251.0
> #;4> (flonum-print-precision 100)
> 15
> #;5> (log2 (expt 2 251))
>
On Fri, Apr 01, 2016 at 12:48:54PM -0400, John Cowan wrote:
> Trying (log2 (expt 2 251)) in Racket, which prints 64-bit floats
> accurately (unlike Chicken, which depends on C to do it)
That's a complete mischaracterisation. First, it depends on your
definition of "accurately", and secondly, you
On Fri, Apr 01, 2016 at 05:25:44PM +0100, Andy Bennett wrote:
> Hi,
>
> In CHICKEN 4.9.0rc1 and 4.10.0 both with numbers 4.6:
>
> -
> #;1> (use numbers)
> #;2> (define (log2 n) (/ (log n) (log 2)))
> #;3> (= (log2 (expt 2 252)) (ceiling (log2 (expt 2 252
> #t
> #;4> (= (log2 (expt 2
Andy Bennett scripsit:
> #;5> (log2 (expt 2 251))
> 251.0
> #;6> (ceiling (log2 (expt 2 251)))
> 252.0
>
> Is it just late on a Friday? Am I crazy?
Trying (log2 (expt 2 251)) in Racket, which prints 64-bit floats
accurately (unlike Chicken, which depends on C to do it) returns
a value of
Hi,
In CHICKEN 4.9.0rc1 and 4.10.0 both with numbers 4.6:
-
#;1> (use numbers)
#;2> (define (log2 n) (/ (log n) (log 2)))
#;3> (= (log2 (expt 2 252)) (ceiling (log2 (expt 2 252
#t
#;4> (= (log2 (expt 2 251)) (ceiling (log2 (expt 2 251
#f
#;5> (log2 (expt 2 251))
251.0
#;6> (ceiling
