🚀 go-pugleaf

Another realistic and usefull example of partial order is
representation of the field R+R (i.e. pairs of real numbers with by 
coordinate add, subtract, multiply and divide. The 'ONE' in this ring is 
the pair {1,1} and the 'ZERO' - the pair {0,0} )

class FloatFloat {
    float first;
    float second;
public:
    FloatFloat(double d=0)              { first=second=d;}
    FloatFloat(double d1,double d2)     { first=d1; second=d2;}
    FloatFloat operator+(const FloatFloat& ff) const
        { return FloatFloat(first+ff.first , second+ff.second;}
    FloatFloat operator*(const FloatFloat& ff) const
        { return FloatFloat(first*ff.first , second*ff.second;}
// etc... all arithmetics
    bool operator==(const FloatFloat& ff)
        { return first==ff.first && second==ff.second;}
//  The templated operator != is good.

    bool operator <(const FloatFloat& ff) const
        { return first < ff.first && second < ff.second;
//  Usual partial order in the R+R ring. Can be used for
//  checking of inclusion of rectangles in graphic software.
//  Here the templated definitions are useless, because of the
//  partial oreder and additional bool operator@
//  (where @ means "non-comparable") could be helpfull)

};