View source for cpp/utility/compare/weak order

====Strict weak order of IEEE floating-point types====
Let {{c|x}} and {{c|y}} be values of same IEEE floating-point type, and {{c|weak_order_less(x, y)}} be the boolean result indicating if {{c|x}} precedes {{c|y}} in the strict weak order defined by the C++ standard.

* If neither {{c|x}} nor {{c|y}} is NaN, then {{c|1=weak_order_less(x, y) == true}} if and only if {{c|x < y}}, i.e. all representations of equal floating-point value are equivalent;
* If {{c|x}} is negative NaN and {{c|y}} is not negative NaN, then {{c|1=weak_order_less(x, y) == true}};
* If {{c|x}} is not positive NaN and {{c|y}} is positive NaN, then {{c|1=weak_order_less(x, y) == true}};
* If both {{c|x}} and {{c|y}} are NaNs with the same sign, then {{c|1=(weak_order_less(x, y) {{!!}} weak_order_less(y, x)) == false}}, i.e. all NaNs with the same sign are equivalent.