Good point about the signed integer overflow, though!

I just wrote a simple loop in C++ to sum up 0 to 2^30. With a single thread without any optimizations it runs in 1.7s on my laptop -- matching Bend's performance on an RTX 4090! With -O3 it vectorizes the loop to run in less than 80ms.

    #include 

    int main() {
      int sum = 0;
      for (int i = 0; i < 1024*1024*1024; i++) {
        sum += i; 
      }
      std::cout << sum << "\n";
      return 0;
    }

- `repr` often outputs valid source code that evaluates to the object, including in the post's example: running `datetime.datetime(2023, 7, 20, 15, 30, 0, 123456)` would give you a `datetime.datetime` object equivalent to `today`.

- Using `_` for throwaway variables is merely a convention and not built into the language in any way (unlike in Haskell, say).

(Hi Jeremy!)

> All of these algorithms take constant time, i.e., time independent of the input coefficients for any particular (n, c).

This means that once you have chosen a particular n and c, the time no longer varies. However, if n and c vary, the running time is definitely allowed to vary also (as the formulas n(c + n) and (c + n)(log cn)^2+o(1) clearly do).

Comments URL: https://news.ycombinator.com/item?id=19744657

Points: 8

# Comments: 0

This sort of optimization reasoning can result in quite surprising behavior: http://blog.llvm.org/2011/05/what-every-c-programmer-should-...

They accidentally turned off auto-throttle and took far too long to react to the falling airspeed.