Infinity isn't really a number so much as a concept. Conceptually, it doesn't really make any natural sense to subtract from it. You can therefore arbitrarily define the result to be whatever is most convenient for your purpose. You could say it's 0, or NaN, or a hippopotamus.
Infinity isn't really a number so much as a concept. Conceptually, it doesn't really make any natural sense to subtract from it. You can therefore arbitrarily define the result to be whatever is most convenient for your purpose. You could say it's 0, or NaN, or a hippopotamus.