[PATCH] Optimize x*x*x*x*x*x using 3 multiplications.

[Paolo Carlini]

Robert Dewar wrote:

>>Optimize x*x*x*x*x*x using 3 multiplications.
>>    
>>
>It is interesting to note that in general this kind of optimization decreases
>accuracy (it is more accurate to do the full 5 multiplications).
>
Indeed, very interesting! If you have got two more spare minutes, I 
would be curious to know a sketch of the explanation of this.

Thanks in advance,
Paolo.