Function: nai ()

Function: nai (N)

Function: nai (N, M)

Function: nai (N, M, K, ...)

Function: nai ([N, M, ...])

Return the ill-formed decorated interval, called NaI (Not an Interval).

Ill-formed intervals are the result of an illegal interval creation, e.g. [3, 2]. They occur if the infsupdec constructor is called with an invalid input and survive through interval arithmetic computations. Boolean comparisons on NaIs return false, i.e. [NaI] == [NaI] is false.

The interval part of NaI is undefined. The decoration part of NaI is ill.

The infsup constructor will not produce NaIs, but a warning instead.

x = nai ()
  ⇒ x = [NaI]
x + 42
  ⇒ ans = [NaI]

See also: @infsupdec/infsupdec.

Package: interval