# Converting a number into an interval: convert

### 5.38.8 Converting a number into an interval: convert

The convert command (see Section 5.23.26) can convert an expression which evaluates to a number to the smallest interval which contains the number.

- convert takes two mandatory arguments and one optional argument:
  - expr, a number which evaluates to a number.
  - interval, a reserved word.
  - Optionally, n, an integer greater than 15 giving the desired number of digits.
- convert(expr,interval ⟨,n⟩) returns the smallest interval containing the value of expr.

#### Examples.

- Input:
  convert(sin(3)+1, interval)
  Output:

  [1.14112000805985..1.14112000805990]

- Input:
  convert(sin(3)+1, interval,20)
  Output:

  [1.1411200080598672220..1.1411200080598672222]