FN0

fn0 is a term that appears across diverse disciplines but does not have a single, universal definition. In practice, it is usually a placeholder or an identifier rather than a formal concept with a canonical meaning. The meaning of fn0 depends on the surrounding notation and the conventions of the cited work.

In mathematics, sequences of functions are typically denoted by f_n, where n indexes members of the sequence. The specific label f_0 refers to the initial function in that sequence. Some informal texts, notes, or code examples may write "fn0" as a compact, nonstandard shorthand for f_0, but this is not standard notation.

In programming and computer science, fn0 can appear as an identifier, often associated with a function stored at position zero in a dispatch table, list, or collection of functions. It can also stand for a zero-argument (nullary) function in examples, sometimes named fn0 to indicate its arity.

Because fn0 is not standardized, readers should consult the source for the intended meaning.

See also f_0, f_n, function, dispatch table, and nullary function.