### 5.37.2 Boundaries of an interval : left right

left (resp. right) takes as argument an interval.
left (resp. right) returns the left (resp. right) boundary of this interval.
Note that .. is an infixed operator, therefore:

- sommet(1..5) is equal to ’..’ and feuille(1..5) is equal to (1,5).
- the name of the interval followed by [0] returns the operator ..
- the name of the interval followed by [1] (or the left command) returns the left boundary.
- The name of the interval followed by [2] (or the right command) returns the right boundary.

Input :

(3..5)[0]

or :

sommet(3..5)

Output :

’..’

Input :

left(3..5)

or :

(3..5)[1]

or :

feuille(3..5)[0]

or :

op(3..5)[0]

Output :

3

Input :

right(3..5)

or :

(2..5)[2]

or :

feuille(3..5)[1]

or :

op(3..5)[1]

Output :

5

Remark
left (resp. right) returns also the left (resp. right) member of an equation (for example left(2*x+1=x+2) returns 2*x+1).