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Re: [gnugo-devel] Patch: improve separation of similarly-valued moves
From: |
Gunnar Farnebäck |
Subject: |
Re: [gnugo-devel] Patch: improve separation of similarly-valued moves |
Date: |
Thu, 22 Apr 2004 02:48:54 +0200 |
User-agent: |
EMH/1.14.1 SEMI/1.14.3 (Ushinoya) FLIM/1.14.2 (Yagi-Nishiguchi) APEL/10.3 Emacs/21.3 (sparc-sun-solaris2.9) MULE/5.0 (SAKAKI) |
Evan wrote:
> Now, a question about my patch... I included math.h in play_gtp.c, to
> get the log2 function. Are there any objections to this?
> Unfortunately, it doesn't seem to work on my system. I get:
>
> play_gtp.c: In function `gtp_move_uncertainty':
> play_gtp.c:3782: warning: implicit declaration of function `log2f'
>
> Am I doing something wrong, or is my system messed up in some strange
> manner?
As far as I can tell that should be perfectly correct but I do indeed
get the same problem. On the other hand, even if it worked there may
be portability issues with log2f(). My suggestion is to rewrite the
function like this (untested):
static int
gtp_move_uncertainty(char *s)
{
float probabilities[BOARDMAX];
int pos;
double uncertainty = 0.0;
UNUSED(s);
compute_move_probabilities(probabilities);
/* Compute the uncertainty as the entropy of the move probability
* distribution, H = -sum(p*log(p)).
*/
for (pos = BOARDMIN; pos < BOARDMAX; pos++)
if (ON_BOARD(pos) && probabilities[pos] > 0.0)
uncertainty -= probabilities[pos] * log((double) probabilities[pos]);
/* Convert the unit to bits. */
uncertainty /= log(2.0);
return gtp_success("%.4f", uncertainty);
}
Hopefully there are not too many portability issues with the basic
log() function.
/Gunnar
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, (continued)
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Paul Pogonyshev, 2004/04/18
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Gunnar Farneback, 2004/04/18
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Paul Pogonyshev, 2004/04/19
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Paul Pogonyshev, 2004/04/20
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Arend Bayer, 2004/04/20
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Paul Pogonyshev, 2004/04/20
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Paul Pogonyshev, 2004/04/20
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Evan Daniel, 2004/04/20
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Evan Daniel, 2004/04/20
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Paul Pogonyshev, 2004/04/21
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves,
Gunnar Farnebäck <=
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Evan Daniel, 2004/04/21
- Re: [gnugo-devel] Patch: improve separation of similarly-valued moves, Gunnar Farneback, 2004/04/14