Hm, (a) this type annotation is unneeded, and (b), `~[]` is being removed so it would be good to take this opportunity to convert to [using `std::vec_ng::Vec`](https://github.com/mozilla/rust/blob/master/src/libstd/vec_ng.rs). Something like
```rust
let mut partials = Vec::new();
partials.push(0.0);
```

and then indexing with (unfortunately) `partials.as_slice()[i]`. Methods like `.push`, `.pop`, `.truncate` and `.len` do not need to be changed.

The new vector is much faster, so this will make this algorithm faster too.