AMCL Observation Model

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Hi! I'm studding some localisation algorithms and now I'm focused in Particle Filters.

I'm using AMCL as a case study. To understand the algorithm and the meaning of the parameters, I had reviewed AMCL source code and read the book Probabilistic Robotics, by Thrun, Burgard, and Fox.

Analyzing the function: double AMCLLaser::LikelihoodFieldModel(AMCLLaserData data, pf_sample_set_t set)

I have some doubts and I like to hear other opinions. So it is here (amcl_laser.cpp):

      //       p *= pz;
      // here we have an ad-hoc weighting scheme for combining beam probs
      // works well, though...
      p += pz *pz *pz;

In the book should be p * = pz but in the code p += pz*pz*pz; Someone understand this option?

And in this line we have:

sample->weight *= p;

And I think that should be (pag 98 of the book):

sample->weight = p;

By the way, can someone suggest another alternative to AMCL?

Chears!!! And thanks in advance!