Sorry for continually remaking this PR, but I think I messed up something small with ghstack that causes this PR to be constantly remade. Can someone stamp this so I can hopefully stop constantly remaking this PR?

It passes the precommit lint check - I think it's fine.

That code is also removed in a couple commits later in the stack.

What happens if b == 1? Perhaps we should at least add a test for that case?

@Chillee merged this pull request in 8002030.

@xuhdev I've done that later up in the stack (I unified all the math tests and added much more exhaustive checkign): #21125

But to answer your question, we return inf, which isn't ideal. Unluckily, there doesn't seem to be any easy way to handle these errors, so we've decided to just fail silently (+ inf is a natural value to return, although it doesn't conform exactly with the python API)