interval -- construct an interval

Synopsis

Usage:

I = interval(n)

I = interval(l,r)

I = interval([l,r])

I = interval(n,Precition => prec)

I = interval(l,r,Precition => prec)

I = interval([l,r],Precition => prec)
Inputs:
- n, a number,
- l, a number,
- r, a number,
Optional inputs:
- Precision => an integer, default value -1, specifies the desired precision of the output, a value of -1 uses the defaultPrecision or the minimum precisions of the inputs.
Outputs:
- I, a real interval,

Returns an interval as small as possible containing n or from l to r. Note that if l is to the right of r, the constructed interval is empty.