Archive for Dieharder

Monte Carlo workshop (Tage 1 & 2)

Posted in Statistics, Travel, University life with tags , , , , , , , , , , on February 21, 2013 by xi'an

IMG_4803Gathering with simulators from other fields (mostly [quantum] physicists) offers both the appeal of seeing different perspectives on simulation and the diffiulty of having to filter alien vocabulary and presentation styles (generally assuming too much background from the audience). For instance; while the first talk on Tuesday by Gergely Barnaföldi about using GPUs for simulation was quite accessible, showing poor performances of the (CPU based) Mersenne twister., when using Dieharder as the evaluator. (This was in comparison with GPU-based solutions.) This provided an interesting contrapoint to the (later) seminar by Frederik James on random generators. (Of course, I did have some preliminary background on the topic.)

On the opposite, the second talk by Stefan Schäfer involved hybrid Monte Carlo methods but it took a lot of efforts (for me) to translate back to my understanding of the notion, gathered from this earlier Read Paper of Girolami and Calderhead, with the heat-bath and leapfrog algorithms. One extreme talk in this regard was William Lester’s talk on Wednesday morning on quantum Monte Carlo and its applications in computational chemistry where I could not get past the formulas! Too bad because it sounded quite innovative with notions like variational Monte Carlo and diffusion Monte Carlo… Nice movies, though. On the other hand, the final talk of the morning by Gabor Molnar-Saska on option pricing was highly pedagogical, defining everything and using simple examples as illustrations. (It certainly did not cure my misgivings about modelling the evolution of stock prices via pre-defined diffusions like Black-and-Scholes’, but the introduction was welcome, given the heterogeneity of the audience.) Both talks on transportation problems were also more accessible (maybe because they involved no pysics!)

The speakers in the afternoon sessions of Wednesday also made a huge effort to bring the whole audience up-to-date about their topic, like protein folding and high-energy particle physics (although everyone knows about the Higgs boson nowadays!). And ensemble Kalman filters (x2). In particular, Andrew Stuart did a great job with his simulation movies. Even the final talk about path-sampling for quantum simulation was mostly understandable, at least the problematic of it.  Sadly, at this stage, I still cannot put a meaning on “quantum Monte Carlo”… (Incidentally, I do not think my own talk reached much of the audience, missing convincing examples I did not have time to present:)