Re: Re: Patches AMD 64 next try...

Dear [email protected],

On Tue, 27 Feb 2007, [email protected] wrote:

> On Tue, Feb 27, 2007 at 10:48:18AM +0100, Wolfgang Müller wrote:
> > On Monday 26 February 2007 16:07, [email protected] wrote:
> > > You and I are getting different results. You're using whats in CVS, and
> > > the one line change i mentioned in the last mail, right?
> > >
> > > i used to run into something that sounds like your bug, but i dont remember
> > > the details, its been months since i messed with it.
> > >
> > 
> > I applied the patches you sent to this list relevant to FeatureExtraction (the 
> > other ones, too), and I found that most of them were already applied in CVS. 
> > So I had the impression of being pretty up-to-date :-) .
> > 
> > I will post my current gabor.c to this list to make sure that we speak about 
> > the same thing. It's at home behind a NAT so tomorrow earliest.
> > 
> > > personally, i break things, then valgrind them to death. i'll let you know
> > > when i have progress with this.
> > 
> > The fact that you said that the output of your stuff was bit-compatible to 
> > David's suggests that David's version had the same bug (yielding some 
> > calculation glitches), but that the optimisations make it become apparent as 
> > segfault on 64 bit.
> > 
> > Cheers,
> > Wolfgang
> > 
> > -- 
> > Dr. Wolfgang Müller
> > LS Medieninformatik
> > Universität Bamberg
> > Check out the SIG MM web site http://www.sigmm.org
> > 
> 
> When i say bit compatible, i mean bit compatible to the one on my 32bit box.

I did understand that. 

Let us look at the loop:

	for (x = 0; x < width; x++) {
	  for (y = 0; y < height; y++) {
  	    int positive = (width*height-1);
    	    int negative = (y*width+x+kernal_size[filter_scale]/2);
	   
	  ...

If the kernal size/2 > 0 then negative *can* get greater than positive
for some values of x and y. Everything else are overflow effects.

...or what am I getting wrong here?

Cheers,
Wolfgang

--
Dr. Wolfgang Mueller
LS Medieninformatik
Universitaet Bamberg