# Can we use theoretically-impossible functions?

Title may be hard to understand, so an example:

If a language claim to have a busy beaver function BB:unsigned int -> double, and works fine(always return Infinity when input is a bit larger and output exceed 1e+310), can we use it as one?

• When/Why would you need to use such a function? – user202729 Nov 20 '18 at 4:33
• @user202729 Designed maybe for fun and used to generate a large number – l4m2 Nov 20 '18 at 7:18