span(List) -- construct smallest interval

Synopsis

Function: span
Usage:

I = span(L)

I = span(L,Precision => prec)
Inputs:
- L, a list, containing Number (including RRi)
Optional inputs:
- Precision => an integer, default value -1, specifies the desired precision of the output, a value of -1 uses the minimum precision of the inputs.
Outputs:
- I, a real interval,

Returns the smallest interval containing the inputs (which can include intervals). Typically, the returned interval is not empty.