ArrTraits::BoundaryCompareYAtX_2

Refines

Has Models

Comparison_result	fo ( ArrTraits::X_monotone_curve_2 xc1 , ArrTraits::X_monotone_curve_2 xc2 , Curve_end ce )
		returns SMALLER, EQUAL or LARGER according to the $$y-ordering of the two curves xc1 and xc2 at $$x = - (if ce is MIN_END) or at $$x = (if ce is MAX_END), with the precondition that both curves have unbounded minimal (or maximal) ends that lie at $$x = ± .