Exact arithmetic with quadratic irrationals

[Timon Gehr via Digitalmars-d]

On 20.04.2017 02:01, Timon Gehr wrote:
>
> My last post includes an implementation of this algorithm. ;)

But in that implementation I used the parameter 'a' instead of the 
variable 'x' as a result of being tired, which makes it slightly more 
confusing than necessary even though it is correct. More readable version:

auto pow(T,S)(T a,S n){
     T r=T(ℕ(1),ℕ(0));
     for(auto x=a;n;n>>=1,x*=x)
         if(n&1) r*=x;
     return r;
}