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Date: Fri, 09 Feb 2007 08:50:56 -0500
From: Brian Hurt <bhurt@janestcapital.com>
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To: ls-ocaml-developer-2006@m-e-leypold.de
Cc: caml-list@yquem.inria.fr
Subject: Re: [Caml-list] Multiplication of matrix in C and OCaml
References: <45CAF3E2.7020807@univ-paris12.fr> <45CAFF5A.2020607@inria.fr>	<45CB3ED0.9040200@univ-paris12.fr>	<20070209.115842.106265091.garrigue@math.nagoya-u.ac.jp> <rkhctvbsz9.fsf@hod.lan.m-e-leypold.de>
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X-Spam: no; 0.00; ocaml:01 matrices:01 printf:01 ocaml:01 gettimeofday:01 gettimeofday:01 printf:01 unix:01 unix:01 caml-list:01 output:02 let:03 let:03 brian:04 brian:04 


>I'd feel better if the code is benchmarked in a way
>that the result of the multiplication is output to a file and to
>subtract the constant contribution of that to the run time that the
>time is measured for various problem sizes (number of matrices). 
>

For the C side, I recommend using clock() to time the runs.  This also 
factors out the cost of creating the random matricies.  Basically, you 
just do:

#include <time.h>

...
    {
        clock_t start, stop;
        ...
        start = clock();
        /* stuff to time here */
        stop = clock();
        printf("The amount of time taken = %f seconds\n", 
((double)(stop-start))/((double) CLOCKS_PER_SEC));
        /* write result to file */
    }

In Ocaml, Unix.gettimeofday can be used similiarly:

    let start = Unix.gettimeofday() in
    (* stuff to time here *)
    let stop = Unix.gettimeofday() in
    Printf.printf "The amount of time taken = %f seconds\n" (stop -. start);
     (* write results to file *)

Brian