Re: [Haskell-cafe] Floyd Warshall performance (again)

From: Mathieu Boespflug

Dear haskell-cafe,

I implemented the Floyd Warshall algorithm for finding the shortest path in a dense graph in Haskell, but noted the performance was extremely poor compared to C. Even using mutable unboxed arrays it was running about 30 times slower. I rewrote the program several times, to arrive at the following definition:

My results are basically the same as Max's, but if I change

#define SIZE 1500 to sIZE = 1500

and all references from "SIZE" to "sIZE", something ... changes. A lot. MacBook-1:Desktop johnlato$ time ./FW Allocating ... Allocating ... done real 0m0.027s user 0m0.013s sys 0m0.014s I can't figure this out at all. Can anyone else confirm, or offer a good explanation? John