root/trunk/units/rational.d

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module rational;

template Tpl(T...){alias T Tpl;}

///
uint gcd(int n, uint d)
{
    if(n < 0) n = -n;
    while(d)
    {
        int t = d;
        d = n%d;
        n = t;
    }
    return n;
}
static assert(7 == gcd(14,21));

///
template Reduce(int n, uint d)
{
    static assert(d != 0);
    static if(n != 0)
    {
        //pragma(msg,n.stringof~"/"~d.stringof);
        const int N =  n / cast(int)gcd(n,d);
        const int D = cast(uint)(d / gcd(n,d));
        const bool Reduced = (gcd(n,d) == 1);
    }
    else
    {
        const int N =  0;
        const int D = 1;
        const bool Reduced = (D == 1);
    }
    alias Tpl!(N,D) V;
}

static assert(!Reduce!(-14,21).Reduced);
static assert( Reduce!(-16,21).Reduced);