- I is an interval.
- x is a real number.

- Returns the upper bound of the interval I. Each bound of an interval has its own precision, so this command is exact, even if the current precision is too small to represent the bound.
- When called on a real number x, sup considers it as an interval formed of a single point: [x, x]. In other words, sup behaves like the identity.

3

> sup(5);

5

> I=[0; 0.111110000011111_2];

> sup(I);

1.11110000011111_2 * 2^(-1)

> prec=12!;

> sup(I);

1.11110000011111_2 * 2^(-1)