I have this tail recursive function here:

```
def fib(n, sum):
if n < 1:
return sum
else:
return fib(n-1, sum+n)
c = 998
print(fib(c, 0))
```

It works up to n=997, then it just breaks and spits a "maximum recursion depth exceeded in comparison" `RuntimeError`

. Is this just a stack overflow? Is there a way to get around it?

It is a guard against a stack overflow, yes. Python (or rather, the CPython implementation) doesn't optimize tail recursion, and unbridled recursion causes stack overflows. You can check the recursion limit with `sys.getrecursionlimit`

and change the recursion limit with `sys.setrecursionlimit`

, but doing so is dangerous -- the standard limit is a little conservative, but Python stackframes can be quite big.

Python isn't a functional language and tail recursion is not a particularly efficient technique. Rewriting the algorithm iteratively, if possible, is generally a better idea.

Looks like you just need to set a higher recursion depth

```
sys.setrecursionlimit(1500)
```

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