Martin Grocholeske wrote: > Hi Søren, >> To which package do you plan on >> adding your functions? >> > Communication package >> To keep the number of inactive developers down we have a policy that new >> developers should post code on the list before they are given access to >> SVN. Could you post you code once you're ready? Perhaps somebody can >> even help with the speed issues :-) >> > Sure. I attached the code. I didn't do it because it isn't publishable > code now and some comments would be nice (I will not commit the > attached code as it is!). I'm not so confident regarding the speed > issues. I vectorized the main bottleneck, but the problem is, that you > have two different task, if you uses a Viterbi algorithm. This task > can only be calculated interleaved or you blow up the memory. > whats the problem?: > - first, you must calculate a path metric (it indicates the > probabilities of the code words), > - second you must decode the most probable message, > then you must start again with the next bit (encoder input word). > > Sure, i'm not the guru of fast octave programming, but i think it's > nearly impossible to make it really fast in octave only. There is a > big big calculation efford and it's hard to vectorize the code, > because you have data dependencies and you need many iterations (It's > a little bit like writing a computer chess is octave). > > If you write C functions, it can be much faster, because you lost the > interpreting overhead. I'm sure this is the way to do. But the fist > step should be working scripts, that will be used as reference for C > implementation later. > > regards, > Martin A colleague of mine at Motorola wrote Octave versions of these function a while back and he felt he couldn't share them.. Perhaps his opinion has changed now that he no longer works there.. In any case vitdec basically has to be an oct-file if you want any reasonable from this code...
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