What is the value of AIC criterion if RSS is 0? The AIC formula is :
$AIC = 2k + n Log(RSS/n)$
So if RSS is equal to 0, it is undefined. How do I deal with this? What value should it take?
RSS = 0 implies that the model is a perfect fit since there was no residual. The limit of the log of 0 is $-\infty$, and since lower AICs are better, and this model is perfect,it makes perfect sense that the AIC should be a negative number such that no number can be lower.