sin()/cos()/tan() for kernel code? '_ 'a

[Alexander Leidinger]

Quoting Stephen Montgomery-Smith <stephen at math.missouri.edu> (from  
Sun, 11 Feb 2007 12:00:12 -0600 (CST)):

>
>
> On Sun, 11 Feb 2007, Stephen Montgomery-Smith wrote:
>
>>
>>
>> On Sun, 11 Feb 2007, Daniel Eischen wrote:

>>> Can't you do this in userland?  Teach moused?
>>
>> Since you will only need sin and cos evaluated to the nearest   
>> degree, if that, I suggest a simple look up table.  There is also   
>> something called the CORDIC method, I think, but I suspect that the  
>>  look up table will be so much easier to program, and negligable   
>> extra space overhead.
>>
>> Stephen
>
> And if you do need more accuracy than the nearest degree, the formulae
>
> sin(x+h) = sin(x) + h cos(x);
> cos(x+h) = cos(x) - h sin(x)
>
> for small h (say |h| less than half a degree) should provide way more
> accuracy than you should need.

There's work underway which moves the hard work of the mouse drivers  
from the kernel to moused. The kernel just has a simple hardware  
interface there, and the real interpretion of all the stuff from the  
mouse happens in the userland.

See http://www.semicomplete.com/projects/newpsm/ for more.

So maybe it would be better to implement this in moused right from the  
beginning...

Bye,
Alexander.

-- 
Love is never asking why?

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