2.3. Unilateral limits

If a and wherein then say x tends to on the left, and write: . Limit call the left limit of the function .

If a and wherein then say x tends to on the right, and write: . Limit call the right limit of the function .

The left and right limits of a function are called one-sided limits . For the existence of a limit function with x tending to is necessary and sufficient to .