Re: [Sbcl-devel] (cos 100000000000000000000000000000000) => 0

[Gabriel D. R. <gd...@in...>]

On Fri, Jul 31, 2009 at 7:21 PM, Harald Hanche-Olsen<ha...@ma...> wrote:
> + Leo <sd...@gm...>:
>
>> In sbcl 1.0.22 and 1.0.27:
>>
>> (cos 100000000000000000000000000000000) returns 0.0
>>
>> In R, it returns -0.4909367.
>>
>> Is this a bug?
>
> Yes, that is a bug (in R): The correct answer is more like -.92073138.
>
> Jokes aside, I think it is clearly unreasonable to expect sbcl to be
> able to return a good approximation because doing so requires
> knowledge of pi to thirty-some decimal places. I can't seem to find
> anything in the hyperspec specifying what the trigonometric functions
> should do when given huge numbers.

Right, the hyperspec does not require a useful Lisp implementation.

-- Gaby