pow calculation in kernel

[John de la Garza]

On Fri, Jun 20, 2014 at 09:55:02AM +0800, 张晗 wrote:
> Hi:
>   
>  I am doing a research on D2TCP(http://dl.acm.org/citation.cfm?id=2342388), I just want to implement it into the linux kernel. When calculating the penalty function, it is p = a^d, where 0< a < 1 and  0< d < 1. Since the kernel only offers integer,   so in my code, so I let a multiply 2^10. But I have no idea of calculating a^d when 0< d < 1. May be I want a  approximate algorithm or other methods. Can you help me ?
>  thanks~
> 

Could you achieve this using fixed point math?

you can see an example in include/linux/sched.h
(search for CALC_LOAD)