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Re: [gnugo-devel] engine/influence.c (and DFA)

From: Dave Denholm
Subject: Re: [gnugo-devel] engine/influence.c (and DFA)
Date: 03 Sep 2002 19:25:26 +0100

Marco Scheurer <address@hidden> writes:

> On Tuesday, September 3, 2002, at 06:11  pm, Arend Bayer wrote:
> > On Tue, 3 Sep 2002, Marco Scheurer wrote:
> >
> >> Speaking of micro optimizations and speed/space trade offs, I've been
> >> wondering about these:
> >>
> >> - There are many bi-dimensional arrays. Would it make sense to replace
> >> them by pointers to pointers? Two indirections are supposed to be 
> >> faster
> >> than the arithmetic needed to access elements in a bi-directional 
> >> array.
> >> The syntax to read an element is the same, but some initialization code
> >> is needed.
> >
> > I think in all performance relevant spots (maybe with the exception of
> > influence.c), we are using one-dimensional arrays since the
> > 1D-transition by Gunnar and Inge early in 3.1.x.
> influence.c still has bidimensional arrays, I think, and even with the 
> 1D transition you still have a multiplication, don't you? Based on what 
> I read a (probably too long) while ago in Numerical Recipes in C, double 
> indirection was faster than multiply, at least on Pentium.

I think cpu performance has increased much faster than memory speed..?


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