Path generation

Posted by Gísli Sigurbjörn Óttarsson KB banki on
URL: http://quantlib.414.s1.nabble.com/Path-generation-tp4816.html

I have been trying to understand path generation for Monte Carlo
simulation.  Specifically, I´ve been wondering about the purpose
of weights.  As far as I can tell, the random sequences that are
used to construct the paths have weights, both on individual points
and on the sequence as a whole.  
 
Mostly these weights seem to be set to 1.0, e.g.:
 
sample_type MersenneTwisterUniformRng::next() const {
    // divide by 2^32
    Real result = (Real(nextInt32()) + 0.5)/4294967296.0;
    return sample_type(result,1.0);
}

Where are these weights used and when are they != 1.0?

Can anyone explain this and perhaps site a motivating reference?

Best regards

  Gísli