Re: [Caml-list] Ocaml sums the harmonic series -- four ways, four benchmarks: floating point performance

[Oliver Bandel <oliver@first.in-berlin.de>]

On Thu, Jan 13, 2005 at 10:53:16AM -0500, Will M. Farr wrote:
[...]
> Here's the code for the fastest implementation:
> 
> let sum_harmonic4 n =
>   let sum = ref 1.0 in
>   let ifloat = ref 2.0 in
>     for i = 2 to n do
>       sum := !sum +. 1.0/.(!ifloat);
>       ifloat := !ifloat +. 1.0
>     done;
>     !sum;;
> 
> let _ =
>   let n = int_of_string (Sys.argv.(1)) in
>     Printf.printf "%g\n" (sum_harmonic4 n);;

I tried harmonic4 on Powerbook G4, 400 MHz and the
native-code needs  about 1 min 50s.

The Bytecode for harmonic4 runs in about 1min 53 s.

It seems that there is no real distinction between
bytecode and native code. At least on that system,
#or at least on that task.


I use Panther OS. It seems that it's more than twice as fast as your OS
(look at the processor frequency: 400 MHz on my PB G4, 800 MHz on yours...).

Which OS are you running? An older version of Mac-OS-X? Or Linux? (which one?)

Maybe you can speed-up your calculations a lot, when installing a different
operating system on your computer.

I didn't try the other implementations.
IMHO you can gain more performance easier, when
changing your OS. Easier than looking at some code optimizations...?!
                                   (which you nevertheless can do too)


Ciao,
   Oliver